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Thread: Noobie here needs Fuel pump help!

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    Default Noobie here needs Fuel pump help!

    Hi Folks, Love the site. Great info! Did a lot of searching so not to waste anyones time...but. No luck yet.
    My Name's JR. I am actually working on this 1976 280Z for a customer of mine. I own a shop that does mechanical resto work on classic cars here in upstate NY. I do love the Z cars and this guy has been to 3 other shops with no help, so I volunteered..How hard could it be right?
    On to the problem. He had a no start, no spark condition when I got it. Figured I needed spark first. Found a bad distributor, Great! Got a new one from Z car source. Now I have great spark, Still no fuel pump. Jumpered pump, (Newer replacement) works fine. Downloaded FSM, started troubleshooting. Actually I took a stab and bought a FI relay. Didn't fix the problem I know better but fixed a lot of problems with just a relay before... Ayway, so I went to the relay testing. 3 tests in FSM. 1st one is testing pin 4 (ECU) to ground in start position. Should have Batt. voltage,Check. 3rd test is for air reg. and FP circuit. Pin 34 to ground= 85.3 Ohms, says should have continuity. Is that number high? The #2 test is for FP relay. Pin 20 to ground, should have cont. I have none with either relay. Says fault is either relay or wiring. If I provide ground to pin 20 with the original relay, I get full time FP running. With the new one nothing. So I did affect a change , just don't know what's wrong.
    Sorry this is so long! Starting to pull some hair out...Could it be my ECU? Or do I need to start opening wiring harnesses?
    Thanks in advance for any and all help! JR.

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    I don't know the '76 that well. Each year was a little different, with different safety mechanisms used to shut off the fuel pump if the engine stopped running. I believe the '76 still used a switch inside the airflow meter. When the engine draws air, the vane opens, and the fuel pump switch closes. Then of course there's the main fuel pump relay.

    The most common electrical problem these cars have is crusty connections. For starters, I'd recommend pulling off all the connectors, cleaning them up, dabbing with a bit of dielectric grease, and reassembling. Then I'd focus in on the connectors that might be problematic with the fuel pump system. Check the big connector to the airflow meter and the one to the fuel pump relay. As you're checking out the FP relay connector, keep in mind that you can short across two of the connectors to deliver power to the fuel pump. I don't know whether the color codes are different on the '76 (re the '78, which is the year I have), but the wires feeding the pump are blue/green. If you short these connectors and the fuel pump fires up, you either have a bad relay or a crusty relay connection. If the pump doesn't fire up, then you've got a connection problem elsewhere. Of course confirm that you've really got +12 on one of the connectors you're shorting!

    If you've got 12V to the relay and no joy with the short, then I'd say check the following:

    1. There are two huge connectors for the wiring harness just inside the passenger firewall, at least on my '78. The FP circuit runs through one of the connectors. Make certain the connector isn't crusty/burnt. Mine was burnt (really an inadequate contact for the circuit), so I snipped it out and used a bullet connector.

    2. Check the integrity of the contacts on the pump.

    3. Check the integrity of the ground, which runs back through the floor to somewhere in the hatch area -- in the toolboxes, I think.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    Thanks "Fast"! You are correct, research tells me the 76 is different than all the later years. Similar in some cases to 75-77.
    Anyhow, yes there is FP activation through the AFM. I should be able to activate it by opening the flap...Doesn't work. The only connectors I haven't checked /cleaned are the dropout resistors. I did try a new FP relay to no avail. however, with the old relay installed I can jumper 1 pin to ground and the pump will activate. No injector fire though. With the new relay, jumping the same pin gets me nothing.. Since the ECU provides the grounds for the injectors I am suspect of that...Maybe I had a bad FI relay AND a bad ECU? Hate to buy one without being sure though. Heading to the shop to check dropping resistors and any other connection I can find. Any other help would be greatly appreciated! JR.

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    I think you're getting ahead of yourself. I thought you had replaced the fuel injection relay (that powers the ECU), not the fuel pump relay (that powers the fuel pump). A running fuel pump vs. an operating ECU are separate issues. Unlike with many EFI systems, the ECU does NOT control the fuel pump in any way. So you need to trace fuel pressure issues separately.

    I wonder whether you bought the right type of relay. If the old relay will actuate the fuel pump, then it's almost certainly working properly. Furthermore, you would have no other wiring issues. Perhaps you plugged a fuel injection relay into the fuel pump relay connector? (I don't know whether the plug configuration looks similar. It's very different on the '78.)

    In diagnosing the system, remember that the fuel pump should only run with the key in the START position, not the RUN position, unless the engine is actually running. If you prop the AFM's vane open and turn the key to ON, I believe the pump should run.

    Diagnosing the EFI is a completely different ball of yarn. To verify injector pulses, pull out a miniature Xmas light bulb ('tis the season!), and plug it into an injector connector. It should flash dimly as you crank the engine -- once per engine rotation. If you unplug the coolant temp sensor, it should flash longer/brighter. To diagnose the EFI, you should download the "Fuel Injection Bible" for the 280Z.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    Wow fast responses! I love it! I did replace the FI relay, but it is a 2 relay box. On the 76 they are together. The connections are correct, believe me I tried to do it other ways. Even tried connecting one plug to the old relay and one to the new. I did buy it from Z car source out west. They seemed to think I was on the right track, but they admitted limited tech help. Took me a while to learn the pump operation only when running, but I got it now. Opening the flap on the AFM gets me nothing. Going to try the home made NOID light trick now too. Didn't have enough battery last night (just got it in the shop late last night). Interesting that the ECU has nothing to do with FP operation...Seems my theory just fell to the ground..lol. I'll go do some checks and check back later. THANKS AGAIN!!! JR.

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    Quote Originally Posted by JRSGTS View Post
    Anyhow, yes there is FP activation through the AFM. I should be able to activate it by opening the flap...Doesn't work.
    There might be a misunderstanding here on the details. The contact switch in the AFM closes (makes contact) when the AFM vane (flap) is opened. This allows power to the relay which then powers the pump, assuming that the initial power sources are correct. If you take the black cover off of the side of the AFM you can see the mechanism. I've had the AFM contacts get contaminated (on a "new" MSA AFM) to where they look like they're touching but they're not really making electrical contact. I had to give them a buffing with a match box strike pad to get them back in order. You can check that the contacts are closing by testing for continuity at the AFM with it removed or at the EFI relay plug (it takes some study to figure out which wires go to the AFM contacts).

    I would check those AFM contacts before going too much further.
    1976 280Z, with some minor modifications

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    Thanks Zed. Just double triple checked those...Even checked for voltage, NP. Have voltage coming out of the AFM as soon as the door starts to open. So here's what else I've tried. Did the Christmas light test on 2 injectors. Tho I'm skeptical of not having an actual noid light, no fire...I double checked the relays under the pass. side. I believe the only one I hear clicking is the starter relay. Double checked connections at fusible links. (Links are brand new) I did find one of the temp sensors not hooked up(the one with the eyelet to ground) I know I need this to run good, but my first concern is getting it to start. I decided to go back to square one. I had done a compression test (190-195 all) but not checked firing order. I was lazy when I installed the distributor and never set for tdc. OK..thats on me... Now that that's right, I even could static time it now. The first time I hit the key it sounded like it wanted to start...But didn't. Though I didn't hear the pump, and still have no pump activation or clicking at the relay. NOW...everytime I hit the key, The starter gives half a crank and the solenoid kicks free!! I can't even get a full engine revolution out of it!!! Hair pulling time! Before I set the timing it would crank all day long...UGH...Doesn't seem logical that the solenoid just died now. Or does it?? The times that I manually powered the pump, I still had no injectors. Didn't try it yet with the timing fixed. I'll also double check the ground wire at the pump. This starter thing has me head scratching good though!
    Thanks for the input! I have to be missing something stupid. If I can get pump and injectors I can then go after all the driveability problems. JR.

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    Sounds like the battery is weak, so your cranking voltage is probably pretty low. I don't know that you can draw too many conclusions without normal voltage.

    Anyway, if you're not getting a full engine rotation per crank, the injectors are unlikely to fire. The ECU counts sparks from the ignition, firing the injectors on every third spark.

    Here's an alternative test: Connect up a wire to the (-) post of the coil, and leave the other end hanging. Plug in the Xmas tree lights. Turn the key to "ON." Now tap the wire to ground. Every three taps should give you a flash of the Xmas tree lights.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    No battery voltage was fine. I had the charger on it all night before., and the charger was on while cranking. Had over 13.0V during testing. The starter isn't kicking out slowly, It tries to spin the motor and instantly goes to a free spin. I get that it needs to spin to fire the injectors, but I should be able to manually run the FP. Car also has a fussy ign. switch that sometimes doesn't crank the motor. Someone installed a starter button. Same result with either starting method. I also checked power at the start terminal on the starter. Solid battery voltage with key in start position. I checked it to see if it was maintaining power and not dropping out causing my starter problem. NP here. Another thing I did was run a ground direct to the black wire on the FP to the battery negative to rule out a bad ground. Still no change. Starter problem or not, I should be able to disconnect the starter wire, the CSV, and hold the key on start to hear the pump run. Or open the AFM flap. Neither gives me a fuel pump!! Getting a bit frustrated.... Thanks for your patience! What about the fact that I have no continuity to ground on pin 20 of the ECU? as per testing the relays in the FI bible? I think I'm going to strip the wiring harness open and trace the wire...Oh yeah, before I fixed my timing issue ( when the motor cranked over like crazy) I had no injector fire then either... Sorry to run on, just thought I'd put as much info as I could out there...
    Thanks again for the input! At least I'm not just standing there staring at it! lol

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    Before you start stripping apart the wiring harness, be warned that half/most of the wires are black -- with tiny little yellow numbers here and there! There are a few internal bullet connections that could be checked, and of course any modifications should be readily apparent. However, I doubt there's much you'll see.

    I think you missed the alternative test for the ECU I mentioned in my last post. It doesn't require cranking the engine.

    Starter issue: You might have an issue with bad switches (even the button that was added) or crusty connections. This is a somewhat common issue in the Z. It might be good to test the starter by jumping the solenoid's spade straight to the + post of the battery.


    I can't help you with pin 20 of the ECU. That pin is not used/connected in the '78. (It's probably not used in the '76 either.) On the '78, I see pins 35, 17, and 16 are the main ECU grounds. Although there are minor modifications between years, I suspect the same pins provide the ground in '76.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    Hi again Fast, No I didn't miss the test. Just forgot to mention that I tried it...lol So many words to type...a lot for 2 fingers . I definately had no flash of the Christmas bulb. Still curious as to how that works on a bulb that is not 12V. I checked with my voltmeter across the inj. connector and there is Battery voltage on both terminals...Is this normal? I am going to get a correct Noid light to confirm. However, I'm fairly sure they are not opening. No clicking from them on any attempt I've made to start this thing.
    There definitely is a bunch of differences between the 78 and the 76. All or most my ECU wiring is white with little tiny numbers on them. The #20 pin at my ECU definitely goes to the FP relay. Found it in the bible, and it is part of the relay testing procedure. Oddly, it says I should have continuity to ground. I do not, with either the old or the new relay installed. BUT with the old relay installed and I introduce ground to the circuit, I get full time fuel pump run. With the new relay....Nuttin...UGH!
    Here is what else I have done. I've been through every connector I can find and cleaned , checked and confirmed continuity through them. I pulled the whole wiring harness down on the pass. side and checked every connector, plug and relay. Even though the bible shows all fuel related components on the drivers side. Cleaned and checked wiring at the dropping resistors. Checked wiring to ignition switch. Everything has been basically clean, I am an ASE certified tech. I know all about bad connections and such. The whole car looks fairly unmolested. The real kicker now is that with the timing and dist. set right the car won't turn over more than 1 revolution without the solenoid disengaging! And yes I've jumpered the start terminal directly. The only thing I can figure is it was a weak starter and when the timing was wrong there wasn't much compression to fight against so it would crank freely. Now that it has comp. the solenoid is too weak...Good news is my local Advance auto lists one at only $29.95 my cost, bad news, won't see it till Sat.!
    Guess I could just walk away till after the holiday. Speaking of that...Happy Thanksgiving To you. One of the many things I'm thankful for is the nice people like you folks who have been so helpful!! JR.

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    JR, the Xmas bulbs are normally strung in a long series. They typically glow with maybe 3V across them. They definitely work, but I admit they're not as refined as real "noids."

    When the key is in the ON/IGN position, the fuel injection relay should connect from +12 to the common sides of the two gangs of drop resistors. The other side of each drop resistor leads to one side of each injector. The ECU grounds the other side to deliver a pulse of fuel. When an injector isn't grounded, you should read 12V across both leads of the injector.

    Regarding the fuel pump relay vs. the ECU: Yes, '76 appears to be different. I'm looking at a color schematic for the '76 at this link: http://www.4moores.com/280z/files/te...ing%20copy.jpg

    It seems the fuel pump relay is part of the electronic fuel injection relay in that year (hence my confusion). There's indeed an input to this relay from pin20 of the ECU. HOWEVER, this input is internal to the relay and would appear to play some role in "keeping" the contact after it is initially "made" via input from 76 (+12 "START"). Pins 20 and 10 are the +12 supply to the ECU. Pin 43 feeds +12 to the drop resistors. So although there is connectivity between the fuel pump relay and the ECU, it's only because the fuel pump relay is part of the EFI relay. In other words, the "logic" of the ECU isn't responsible for actuating the pump, if that makes sense.

    It's interesting you say that you get a running fuel pump when you introduce ground to the circuit. Are you saying it's when you ground 72 of the relay? If so, that would indicate you have an open ground. To be clear, the relay should be actuated when you introduce +12 to 47 ("START"). The ground should be continuous.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    YES! It has to be a ground...I think..lol When I ground 72 I get FP...I will make sure I get feed on 76. But I did cont. check on 20. There is no open between the relay and the ECU, so where am I losing ground? Ran a fresh ground to the pump, the engine, the ECU case ( Just in case lol) As far as the Christmas bulbs go, should I be using a whole string? Cause the one little bulb blows real easy when it hits 12V!lol
    Love the colored schematic! Wish my stupid printer would communicate! It's on holiday. Guess that's what we should all do. Have a great turkey day! I'll check in with progress on Friday. Thanks again! JR.

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    Sounds promising!

    I have no idea how literal the schematic is, but if you take it at face value, the ground runs all the way back to the battery and is the same branching ground system that grounds the ECU. That could be your smoking gun right there.

    I'd first check the connections off the battery for obvious reasons. However, the branched connections in the wiring harness are crimped and wrapped over and are possibly also subject to corrosion. You might want to unwrap the wiring harness enough to find all these branch points and verify they are clean/good.

    Don't worry about the fact that 12V will blow a bulb. A straight 12V will melt down an injector the same way. Remember that you have drop resistors wired in series to limit the current flow! Just use a single bulb, and you'll be fine.

    Have a great Thanksgiving, JR!
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    JR.

    FYI, you can stop worrying about pin 20 going to the ECU. It's not even connected inside the ECU. My thoughts on why are that Bosch engineers were planning ahead to control the FP relay at some point via the ECU, but for your year model, they didn't. If you look at the ECU connector (Not the harness, the ECU itself), most likely there won't even be a pin installed in location 20. (Some do, but most of the 75-77 ecus I have taken apart don't have pins there). And, even if the pin is there, it's not connected to the circuit board inside.

    The ONLY ground you need to worry about on the relay is pin 72 on it. Both internal coils ground through this connector. If you have good gnd there, the relay will be satisfied. Here's the path for the fuel pump to turn on via the flap.

    1. Bat + at pin 70. (all the time regardless of key pos)
    2. You turn key to ON. This first one coil inside the relay block and connects p70 to P43 (dropping resistors), & P39(one side of AFM switch) P43 and P39 are connected inside the relay.
    3. Now move the AFM vane. This runs the +12v back to the relay onto to Pin36 which fires the second coil in the FP relay. That relay will then close and connect P73(+12 via fusible link) to P74(the pump).

    If I were troubleshooting I would do these in order.

    1. GND pin 72, hot wire +12V to pin 36. (This should FIRE fuel pump by connecting p73 & p74)
    2. If that works, then your problem is with the signal getting to Pin36 by way of the AFM switch.
    3. If that doesn't work, then you either don't have +12v reaching pin 73 via the fusible link or the relay it'self isn't passing the signal to p74 or the wire from p74 to the FPump is open, or the pump doesn't have ground.

    Another way is to work backwards with a +12V jumper wire.

    1. With the key OFF.
    2. Jumper +12V to P74 (pump should run - as P74 is the actual wire going to + side of pump)
    3. Jumper +12V to P36 (pump should run ) - tests one of internal coil/contacts of relay
    4. Jumper +12V to P39 & Move AFM flap off idle (pump should run) - tests AFM contacts

    5. Now turn key ON & Move AFM flap off idle (pump should run) - tests the second internal coil/contact.

    I'll be heavily involved in fuel pump relay wiring & general purpose ECU testing Friday. If you are working on it then, PM me and I can give you contact info to call me. With a diagram in front of you and some quick conversation I bet we can figure it out. The Z's relay scheme isn't quite straightforward, but once you wrap your head around it, it makes sense.

    Happy Turkey Day!

    Lenny

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    Wow!! Thanks so much Lenny And Sarah!(I checked your profile so I didn't keep calling you Fast Some really great info, and lots more tests to run! I'll dive in fresh and well fed fri. AM. If I'm still head scratching Lenny I'll PM you.
    I'm wishing you and yours a very happy Thanksgiving!

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    You're quite welcome, JR!

    I think once you get this Z running, you will fall in love with it and have to own one yourself.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    You are quite right Sarah! Though I would likely drop a small block chevy in it An early 240 with about 350 Hp could be one helluva ride!
    Sorry I couldn't give an update today... Between getting the step daughter to emergency dentist appt. and all the other things to do, I got about a 1/2 to look at the car... I had a used starter to try for the fun of it to see if it changed my cranking problem...Yah..fun..easy swap. just had to try it. I'll have a new one tomorrow.
    Did a real quick run on your tests Lenny. Post results tomorrow...Yup something's real wrong...I'll be in touch.. JR.

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    Nooooo! The Z doesn't need a small-block V8! The L28 is a beautiful engine. You'll see. But of course I'm a sucker for a nice inline-six.
    JRSGTS likes this.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    Quote Originally Posted by JRSGTS View Post
    An early 240 with about 350 Hp could be one helluva ride!
    That's true. There's one right up the street from me. A very nicely done 280 with an LS1. Somehow, though, it still just doesn't seem right to me........
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    NICE!!! Good to know...
    Here's the latest..Fighting a lingering tryptofan (sic) hangover. I went to the shop..12 degrees here, Toasty in the shop. Just another excuse to be lazy. I saw the starter was dropped off so I had to go to work.. Installed the starter, YAY cranks normally now! Even acts like if it had fuel it would run. Sputters a little and smells like the plugs are burning whatever they can find.
    Lenny I did your tests. It failed the first one. went to ground P72, started letting the smoke out of my jumper wire! There is Battery voltage there...That's not right. Moved on to your backwards trouble shooting. 12V to P74=got pump.but, 12V to p36=no pump. and 12V to p39and move AFM flap+ still no pump. I also rechecked again for inj. pulse now that I have normal cranking= Nothing. tried to start it while p72 was grounded and pump running, Nope. didn't expect it to, had to try it.
    Obviously 12V at 72 is a problem,Hopefully you can give me a direction. If it's not wiring I'm still leaning towards the ECU because of the no INJ. fire. The owner tells me it was running fine, drove into his drive way, and it never started again.
    I've got to go to the neighbors for their printer to get the Schematic printed. My printer is still on holiday.
    BTW, I posted some pics of my shop on my profile if you want to see some of my work.

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    Quote Originally Posted by sblake01 View Post
    That's true. There's one right up the street from me. A very nicely done 280 with an LS1. Somehow, though, it still just doesn't seem right to me........
    I get it. I respect the purist mentality completely. I ALSO love the dare to be different, and the right of choice with customizers. Lots of Ford people hate seeing Chevy's in Hot Rods. I say if it works for them, go for it. Besides, the LS1 is an amazing engine! Bet that car is way cool and makes more HP than that Z ever imagined. Of course it opens a whole can of worms for other issues. Congrats to him on his bravery! lol

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    https://scontent-a-ord.xx.fbcdn.net/...55525336_n.jpg Here is the little gem...Hope this works...Not very Forum tech savvy

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    JR,

    Something definitely not right here. P72 should be connected to GND already in the harness. If you are seeing +12V there, we have an issue already. P72 is the ground side of both coils in the relay. This would also explain why (12V to p36=no pump.) as the coil gets +12V from you on p36 via jumper wire, but the other side of the coil isn't grounded. The following tests would be of no use until we figure out why P72 is showing power.

    This same ground is the ground for the ECU as well, so that might also explain why the ECU is not firing injectors.

    One thing I might bring up is that Datsun did some crazy color schemes on the FI harness power supply. Such as the ground wire (The same one I'm talking about) where it connects to the battery is a large 8awg or so "RED" wire. Sometimes its Black, but I have seen them RED. Where it connects to the battery is just a big spade connector (stock) but might have been changed over the years, but someone could have mistook it for a power connection and have it connected to +12V instead of gnd. It runs right up to the battery & looks like it should be tied to +12V because its' red.


    To find out, pull the connector off the ECU and measure the voltage at pin 35. It should be GND. Actually pins 35,17,16 & 5 at the ECU connector are all tied directly to GND. If one of these is gnd all should be.

    Lenny

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    Well... If there is discontinuity between 72 and GND, it should read +12, and grounding 72 would result in current flow. But perhaps we're talking about a lot more current flow than normal.

    I think Lenny's theory about the red GND wire is plausible. I was shaking my head about that color code in the color schematic.
    My last three sports cars while I still owned all three:

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    Quote Originally Posted by JRSGTS View Post
    has been to 3 other shops with no help, so I volunteered..How hard could it be right?
    On to the problem. He had a no start, no spark condition when I got it. Figured I needed spark first. Found a bad distributor, Great! Got a new one from Z car source. Now I have great spark, Still no fuel pump.
    Who knows what the other three shops did but it seems like the ground connection at the battery would be okay since the electrical system is right enough to give spark. And he has a good starter now. Looks like he's down to the fairly typical problems of no injector activity and problems making the fuel pump run.

    The ECU grounds the injectors base on the discharging of the coil with voltage pulses transmitted through the wire from the negative post of the coil to Pin 1 of the ECU through the blue wire. The tachometer and its in-line resistor need to be in place for the ECU to do that correctly (in case you have some things torn apart).

    Of course, the other half of that relay is the EFI relay. Have you measured voltage at the injector connectors with the key on? You should have 12 volts on both sides. Which I see that you have in Post 11. Check the circuit from the coil negative to Pin 1 at the ECU. You should have continuity.
    1976 280Z, with some minor modifications

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    Quote Originally Posted by superlen View Post
    JR,

    Something definitely not right here. P72 should be connected to GND already in the harness. If you are seeing +12V there, we have an issue already. P72 is the ground side of both coils in the relay. This would also explain why (12V to p36=no pump.) as the coil gets +12V from you on p36 via jumper wire, but the other side of the coil isn't grounded. The following tests would be of no use until we figure out why P72 is showing power.

    This same ground is the ground for the ECU as well, so that might also explain why the ECU is not firing injectors.

    One thing I might bring up is that Datsun did some crazy color schemes on the FI harness power supply. Such as the ground wire (The same one I'm talking about) where it connects to the battery is a large 8awg or so "RED" wire. Sometimes its Black, but I have seen them RED. Where it connects to the battery is just a big spade connector (stock) but might have been changed over the years, but someone could have mistook it for a power connection and have it connected to +12V instead of gnd. It runs right up to the battery & looks like it should be tied to +12V because its' red.


    To find out, pull the connector off the ECU and measure the voltage at pin 35. It should be GND. Actually pins 35,17,16 & 5 at the ECU connector are all tied directly to GND. If one of these is gnd all should be.

    Lenny
    THAT"S IT LENNY!!!!! Has to be! Brilliant! I hadn't got a good look at the wiring diagram yet because I couldn't print it. Even at my inlaws on there PC, I could only print small hard to read pieces...OK my only question now is Which 8awg. wire is it? I have 2, both run to the Battery+ One still is in a big stock spade connector. The other has been spliced to the lead on a replacement battery cable. The wire must change colors before the ECU because there is no red wire there. Definitely the problem. NONE of the grounds you or Sarah listed are grounds right now. I hope no ECU damage has been done. Oh yeah, P1 does have cont. to -coil.
    Funny how the owner says it just wouldn't start one day...Someone had to mess with the battery leads first... That's why I take customers descriptions of problems with a grain of salt. Going out to see if I can figure which wire..I'll report back soon. THANK YOU!!!

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    Couldn't wait...Ran out and switched the ground. Suddenly I have FP when I test in run position, I can fire it with the AFM flap, I even have inj. pulse!!! Bad news is it won't even try to start...Think I have wasted plugs, I know I still need one of the temp. switches. I thought it would try harder... I'll have more time later to mess with it, but you have definitely fixed my big issue!! Thank you, Thank you thank you!!

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    Oh yeah..we be all kinds of flooded, But it's going to work! Awesome Lenny! Of course now I go back and look at the wiring and see the big gang of them heading for ground! Then look at my car and see the link headed for + and not see The problem! Always clearer looking backwards with someone else's eyes..lol.
    I will go tomorrow and get plugs, FF. Fresh oil and filter(Heavily contaminated, so I really don't want to run it today anyway) Cap, rotor, wires, look fine. I do need the "Water temp. switch" The one with the eyelet ground wire. Which corroded enough to break the bolt. I'll rerun that some where. The blue lead was broke off. I can't find it on the wiring diagram. See all the other sensors...(Thermotime, AAR, water temp,CSV) But not a temp. "switch" Any hints..?
    Any way, I'm really confident That you found it for me and this problem is Kicked in the butt! Winner, Winner I always say! Now I can sell him on the rest of what this car needs! But for now it's time to enjoy a Sunday and watch some Football!!
    Sarah,Lenny, Zed, Thank you very much. This place is way cool, cool! I'll be sure to post some up and running shots.
    JR.

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    OK Last comment! Found the temp switch on the diagram finally..(Old eyes!) Np there. I'll get a switch or at least rewire this one before I try to refire.
    NOW, On to couch potatoe / football land!

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    Glad you found a solution although I have to say it doesn't make sense to me. The small gauge wire from the positive post is the EFI power supply. I can see how not having that connected would allow everything to work except the EFI components. But connecting the EFI power directly to the small gauge ground spade should have caused a short. I think.

    Maybe that is the EFI ground only and its isolated from the others. Or maybe yours is not connected to anything and you got lucky. The diagram shows it as connected to body earth so there should have been big sparks as soon as the small gauge positive was connected to it, shorting back through the large negative cable.

    Anyway, good luck and carry on.
    1976 280Z, with some minor modifications

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    JR,

    Glad you're on the right track now. I don't think you harmed the ECU. It's possible, but it was wired with +12V on both the supply and ground on the ECU, it wasn't reversed so I think it will be fine. No other parts on that gnd circuit would be damaged by the miswiring. Just check for injector pulses. If you are getting any at all the ECU should be good enough shape to get you started.

    Lenny

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    Wow, fantastic! You're not out of the tunnel yet, but at least you can see some light. And yes, a red ground wire.... Hmmmm.... What could go wrong?

    Giving the PO the benefit of the doubt, perhaps something besides the ground miswiring kept the engine from starting/running after setting up. Then one of the other three mechanics screwed up the wiring -- probably the first one.

    Anyway, it sounds like you'll have it running in short order. Now we're beyond the weird modifications made by gremlins, and it's just a matter of trading down component failures.
    My last three sports cars while I still owned all three:

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    I feel compelled to emphasize for any future readers of this thread, do not switch the positive and negative small gauge wires at the battery in an attempt to fix a "no injector pulse" or "no fuel pump power" problem. Bad things might happen. This thread is a special case of lucky.

    There must either be a mistake in the wring diagram or the car in this case has a ground wire that is not actually grounded. I have a 76 and will check that ground wire when I get a chance to see what's what, but the solution here is not quite right. It bugs me.
    1976 280Z, with some minor modifications

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    Good to have a disclaimer. Just to clarify. The car had BOTH the Pos. And the Neg. ECU leads on the Bat.+ I took a guess at which was which and got lucky. Now I have proper FP activation, and injector fire.
    Now here's the update: Typical Monday, couldn't get new plugs till 11:30 unless I wanted Autolite's. No, waited for the NGK's Did try it with the old plugs now that they dried out...Barely tried. I did rewire my temp. switch, changed the oil and filter, Buttoned up all the wiring, Double checked inj. pulse on #1 and #6, good fire, but the bulb is quite bright...? Wish I could read Data on the coolant sensor to see what it thinks it is..I have a feeling it's out of range. Plugs getting very wet very fast. Got my new plugs, but they only sent 4...Figures. Tried them a couple times but didn't want to foul them. No luck. The fuel is definitely old. I've run cars on worse smelling, but I'm going to eliminate the variable and drain the tank and lines. Kill time till the other plugs get here. I did try to start it without the CSV in case it is flooding. Might have seemed like it helped a little but still no start. I'll go get fuel smelly and report back later...
    JR.

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    +1 on what Zed said. This is definitely a special case. And JR...eeks on guessing 50/50. Had you been wrong you would have reverse biased the ECU. I'm not sure if that will kill it or not, but its not a great idea. I'll have to try with one I have lying around. I hope at least it was an educated guess.

    Zed.

    One thing that I have noticed on all of the FI harness' that I have looked at is that this ground wire is not connected to the frame anywhere. It is only connected to the battery (-). In the FSM it shows a star ground where all the wires connect, but I think that is just referring to the splice in the harness not an actual physical star ground to the frame. I think Bosch was trying to isolate this circuit from everything else in the car. The ECU case gets grounded to the frame when it's bolted in, but the case isn't connected to the gnd on the circuit boards inside.

    The schematic I'm referring to is the one in the '77 FSM & the Z EFI theory/troubleshooting.. I haven't checked others, they may show it as a star gnd to frame. And the one in the FSM could certainly be interpreted as a frame grounding point. I've just never seen the frame gnd in the wild.

    Len

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    Wasn't too hard a guess because the original spade conn. was still in tact and I read ..Somewhere That there should be one in that line.....AND still never clued in to it going to the wrong Batt. post!! UGH...
    Moving on.. I heard it run!! As predicted Sarah, It runs like crap... I changed out all the old fuel.(Full tank!) Blew out the lines and filter.( now new). Installed NGK'S Barely firing. My "fix" for the coolant "switch" didn't work. The wires broke off too short. Auto parts can't find me one. I really don't want to wait a week for another. What does this thing do? The FI bible doesn't talk about it. I do have a new coolant "Sensor" coming in the AM. The other similar looking sensor the thermotime switch correct? The only way I could make it run was to advance the hell out of my timing, I know I'm rich as rich gets. Can this ALL be the coolant sensor?
    Really cool stuff you're doing len with the ECU build. Been following it..Not understanding a lot, but I get the idea. Love that cam, crank sensor, with COP idea!
    Any help on the sensor stuff would as always be appreciated!! JR.

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    Another quick question? Does this system have any kind of diagnostic link? Is there any way to read data?
    And I mean like Data I can read like basic sensor's and such... JR.

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    Realized that I was looking at the wrong wire in the 76 diagram. There are three connected to negative, the big cable to the starter lug, a wire to ground, and another (the one we're talking about) which connects to 5, 16, 17 and 35 and the coolant temperature sensor. A dedicated isolated ground for the EFI system, apparently. 5 is also connected to 72 of the EFI relay. In short, the star ground shown in the Engine Fuel chapter, with 5, 16, 17, 35, 49 and 72 is actually the dedicated wire to the negative post. If that wire is disconnected, parts or maybe all of the EFI system is not grounded. New learning for me.

    superlen must know this but I was never sure of what that wire was connected to. I sure didn't know that it was the ground for the coolant temperature sensor. It should be a focal point for anyone seeing high resistance on the coolant temp. circuit.

    I went out and measured resistance from that small gauge ground wire back to the battery negative post and got 63 ohms. Resistance from the negative post to the valve cover was 0.7 ohms (control measurement). I assume that I was measuring resistance back through some resistors or transistors to ground. So, connecting those wires backward at the battery may or may not be guaranteed to cause damage. It's not a direct short but it's not open either.


    Had to write all that down just to burn it in to my brain.
    1976 280Z, with some minor modifications

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    Quote Originally Posted by JRSGTS View Post
    Can this ALL be the coolant sensor?
    The coolant sensor is one of the major control components in the EFI system. If it's not connected the ECU "assumes" that the engine is stone cold and that it's in Antarctica. It has to be connected and working correctly to even have a shot at the engine running right.
    1976 280Z, with some minor modifications

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    +1 again on what Zed said about coolant sensor. The cold start valve could also be a contributing factor, but I think you're on the right track with the coolant sensor wiring. You can take the cold start valve out of the equation by pinching off the fuel line going to it with a pair of small vice grips. Then if you are still running way rich you will know its just the ecu.

    Oh, and there is ZERO diagnostic feedback from the ECU. It's only function is reading inputs & firing injectors. There is no way to read sensors & not even an idiot light to look at. That's another reason I wanted to do the HellFire project.

    Len

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    +2. Yeah, the coolant temp sensor is THAT important. With an open circuit, the engine will be blowing thick, black smoke out the tailpipe. The reason the "noid" bulbs flash very brightly is that the injector pulse is very long. This usually indicates a CTS open circuit.

    I would suggest you measure the CTS resistance from the ECU connector, as that will confirm that all your connections are also good. As Lenny points out, there are no diagnostic capabilities. The ECU actually has analog circuitry, not digital! So the way you get data from this EFI system is with a multimeter and/or oscilloscope.
    My last three sports cars while I still owned all three:

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    Cool, Cool so I'm on the right track. I am still unclear on what the temperature "Switch" does. It appears to be wired to one of the relays on the pass. side inner fender. According to the color Schematic the bullet connector is red. The lead off the sensor is blue?? There is a red lead coming out of the harness on top of the intake, but it is way too short. I also have one pair of bullet connectors coming out of the harness near the temp. sensors, one white, one black. Any ideas?
    I'll let ya know how it runs after I get the sensor in. THANKS!! JR.

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    Different years did different things with different versions of a temperature switch. How's that for an all inclusive statement?

    In 76, the temperature switch controlled spark timing on the non-California dual-pickup distributors (see page EE-26 of the 76 manual) and it also controlled actuation of the EGR system (see page EC-11 of the 76 manual).

    Basically, they advance the timing and disable the EGR until the engine warms up to the temp at which the switch opens.

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    HMMM, well I have a Non California dual pick up dist. Seems I'll need this to work...Guess I have to find one somewhere...Any clue on the wiring. Should it go to the red lead? It (the red lead) traces back to the relay as per the wiring diagram, but doesn't reach. Maybe there was another lead that is missing? I can make one NP, just trying to make sure....

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    Could be why I had to RETARD my timing so much...I know I said that wrong in my earlier post, I always phrase it backwards.. If I don't have an EGR valve, it must control spark adv. in my application correct? So there is probably no living without it.

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    OK, Coolant sensor made a LITTLE difference. I can make it run. Starts barely. Sounding like it's running on 3 cyl. gently rev it and the others come alive...Still eye tearingly rich with black plugs. If I jumper the red lead to the temp control relay it runs better. I must need that sensor pretty bad. Doesn't seem like all of it though. Looking back, my AFM resistance checks were a bit high. Could that be bad? I know there is an air temp sensor in there too. Trouble codes and data would come in real handy right now! I did actually move it under it's own power! Progress I guess.
    Need a "Hell fire" test mule Lenny!?

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    It's quite possible your cold start valve is stuck open, either because it's jammed up or because the thermotime switch isn't working properly. That could be the source of your eye-stingingly rich mixture. (Pinch off the hose to see if the engine runs better.)

    Also check the throttle position switch for proper operation and adjustment. You might be getting WOT enrichment, which still wouldn't account for eye-stinging richness, though.

    Finally, you might run some Chemtool B12 through the system to clean up all the injectors. Maybe they're sluggish?
    Last edited by FastWoman; 12-03-2013 at 08:33 AM.
    My last three sports cars while I still owned all three:

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    Thanks Sarah. Wondering when I'd find you on here... I'll try those tips. It will start better with the CSV unplugged. However I still am clueless on this coolant switch. Can't find one anywhere easy. I'll call Zcar source but it will be a week out...
    Came up with another question..lol Should this car have an O2 sensor? Cause it doesn't....

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    Looks like you're using the EFI Handbook for your testing. The Handbook is a generic document for the 280Z's and/or the 280ZX's, depending on which version you have (1975 or 1980). You should start working from the FSM, with its information and diagrams that are specific to 1976. Read the first few pages of the Engine Fuel chapter and the Emissions chapter. They describe all of the weird little devices that you're working with. Then do your circuit testing from the ECU connector. Then you'll know if the wires and connections are adding resistance or shorted.

    Many people remove the CSV system entirely, the switch, the valve and the fuel lines. Cars are designed for a very wide range of environments, and I think that the CSV is for people in the mountains or the midwest. If you're worried about it being stuck open causing richness, just block the fuel line for a test.

    Index of /FSM
    1976 280Z, with some minor modifications

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    I'll try that. I was able to move it. Starts like crap, but sorta clears at higher RPM. The owner came by and I tried to show him...It started on 3 cyl. then never cleared. Now it won't even try!! UGH. and that was with the CSV disconnected. With the plug off it can it still spray fuel? I suppose if it was stuck open right? I don't think that's my big problem any way because I was seeing such a bright"Noid" light. Could my AFM be the culprit?
    Also, have tried nearly everywhere for a coolant switch...Not in production for the 76 anymore....UGH!B I'm walking away to get the fuel fumes out of my head...

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    It's really hard to emphasize!!!@@@## how much better and smarter you'll feel!!! if you run the resistance test for the coolant temp. circuit from the ECU connector!!! Once you know that the ECU sees what it should see!@#$#% then you can stop guessing and buying parts @#%%$

    Seriously, just unplug the ECU connector, measure resistance to ground at the right pin (13? I believe, it's in the Engine Fuel chapter) and compare the number you get to the chart in the FSM (it's in the Handbook too I think).


    You can do many of the other component checks also, like the injector circuit, Pin 1 to coil, etc. It's much easier than it seems and really, it's where everyone should start.
    1976 280Z, with some minor modifications

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    I promise I'll do that as soon as I PUSH it back in the shop... I had to move it out to finally get some other work done around here.... I did go back before dark after leaving the plugs out a while and letting it dry out a couple hours. It was probably in the upper 30's by then. Put the plugs in, lots of battery, rolling over fine. It barely tries to start maybe twice, then nothing, just spinning won't even sputter. This is with the fuel line to the CSV removed and plugged. I check the inj. #1 and #6 I'm getting wicked bright flashes every third....Then it goes to dim flashes. First time I have ever seen it do this. Checked both inj. Same result, so I think great it won't flood out. Keep trying to start, won't even try... Figure it's already flooded, pull the plugs. They're not that wet....Blow out the Put all the plugs back in the wires and spin the motor. My sparks all F'd up! I got fire on 6 and 1, intermittent on a couple others, The battery starts to tire by then, I just threw some hair at it and walked away...
    I will do the resistance test. But the sensor is new now. I doubt there is any issue there. Something is/was firing my injectors way to much. I do plan on pulling the whole rail off and see how they fire and if they leak. I wish the damn thing could at least spit out codes. I'm wondering if the ECU was hurt from being wired wrong? Who knows who jumped power and grounds where before I got here.
    I really am sorry for how long this has dragged on. I'm very grateful for all of your help and patience.
    JR.

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    JR,

    You may be at the point it's time to swap out with a known good ECU and make sure it didn't get tweaked a little too much with whatever crazy wiring combinations it had before it reached your shop. If you don't have one available, pm me. I have a few and can ship you one to test with. I just need it or your old one back after you test.

    Also the resistance check will confirm the wiring connection from the sensor to the ecu. The pigtails up there are a problem area & this test will confirm that they are either good/bad.

    Lenny

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    A worse problem spot than the pigtails, IMO, is the (very likely) crusty and half-rotted Bosch-style connector that mates to the spanking new coolant temp sensor. It takes quite a lot of abuse up there at the front of the engine. The connectors on my thermo housing sensors were in crumble-in-your-fingers condition, with a lovely green patina on what was left of the metal bits. Replacements are plentiful enough. Check out this ebay auction for a complete EFI harness connector replacement kit! Woohoo!

    A10B1F1 Datsun L6 Wire Harness Connectors Repair Kit afm TPS Fuel Injectors | eBay

    And I've bought the two-pin connectors from this guy, who is an upstanding gent:

    Injector Connector Kit 6pc Datsun 280z 280ZX 300zx | eBay


    There would be no reason I can think of for the injection pulse to be very long (bright flash) and then drop to very short (dim flash), OTHER THAN an intermittent open circuit on the CTS circuit. Well, either that or the ECU is bad. My vote would be for the bad connection.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    I've had one bad ECU and its death characteristics were to die instantly, come back to life for about 1/2 mile, die again, start again, die again, flood the engine with fuel, then never start again. I replaced the two injector transistors and got it to work again (just for fun, not because I knew what I was doing) but have only taken it for a test drive since then.

    Something to consider is that the transistors used for the injectors are very similar to those used in the ignition module, and ignition modules do weird things before they crap out for good.
    1976 280Z, with some minor modifications

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    Len, That sounds very helpful! After I get it back in the shop and do those other tests, I will let you know. Sarah, The connector was intact with a Minor bit of visible oxidation. I have some micro files, so I cleaned it up real good. The plastic and the wire clip are still in decent shape. I will confirm all condition with the resistance check. I did see the connectors on Ebay. I was looking for a temp. switch. (They don't exist anymore). I think I can buy those connectors at Advance also should I need one.
    Zed, I am concerned about the ign. Module, and or the dist. pick ups. Z car source just rebuilt this distributor, so I really hope its ok. Don't know if all this abuse has hurt it. When I pulled it out of the shop it would run, terribly, but it would run. I was trying to start it for the owner, it tried then stopped even trying. Something let go. Not surprising. This thing is beginning to get to me...

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    Another thought, What about the air temp sensor in the AFM? The AFM passed the resistance checks and a saw change on my meter with flap movement. Though I didn't watch it carefully to see if it was perfect or not. I saw resistance drop so called it functional, but doesn't the temp sensor have bearing on inj. pulse?

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    The air temp sensor plays a much more minor role in fine-tuning the mix. I doubt a problem with that sensor would result in the magnitude of problem you're having. Besides that, I don't recall anyone ever having a problem with the thing going out or suffering a bad connection (via the AFM connector). FAIW, I think it has the same thermistor as the CTS, and yet it lives a much more sheltered life.

    Regarding the distributor pickup: If you've got spark, it's working fine. Apparently the biggest problem with the distributor pickup is setting the gap correctly. Some rebuilds have too wide a gap. Worse, some rebuilds come back with a bent shaft that wobbles and yields an inconsistent gap.

    Reason to believe your ignition is working fine: You're getting the "noid" flashes once per rotation, right? Without the ignition firing (which requires triggering by the distributor pickup), the ECU wouldn't count and wouldn't inject. As RPMs increase, the distributor pickup should put out a cleaner, higher-voltage signal, so if the pickup works well enough when you're cranking, it should work even better when the engine is actually running.
    Last edited by FastWoman; 12-04-2013 at 08:51 AM.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    But honestly, you should just read the #13 pin resistance at the ECU. Just remove the interior driver kick panel, and there's the ECU. Pull off the big, hunkin' connector, and the world's your oyster. We can't emphasize that enough! (Well, Zed gave it a pretty good try, I think -- post 52. ) Nothing will tell you what the ECU "sees" like measurements taken from that connector.

    Oh, and you had asked about the O2 sensor. (Had that been answered?) The Z don't need no stinking O2 sensor (to paraphrase the movie). The ECU only has open-loop mode, with no lambda feedback. Primitive!
    Last edited by FastWoman; 12-04-2013 at 08:57 AM.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    OK...Thank you Sarah for all the input! Give me some relief about the Dist. and the AFM. First and foremost, I did the resistance check on #13. Good memory Zed. I had 3.53Kohms to ground. Guess that's continuity. And as I recall I tested resistance between the pins on the sensor before I installed it and it was right around the same. I could not find the "chart in the FSM, but did find the test. All it says is I should have cont. or suspect a bad CTS. I also went through and re-cleaned the connector,pigtails etc. Checked my plugs again. They must have fuel fouled bad, but between the 2 sets I got fire on all 6 before reinstalling. Barely ran. Couldn't even get it to clean out like yesterday and act like it was running on all 6...BUT, guess what.. Rechecked with the noid light..Back to super bright flashing!! The owner brought over another AFM he had, but it was from his 83 engine. missing pins 36 + 39 so that's no help. I'm pretty convinced it's not the problem now anyhow. Pm'ing Lenny about an ECU...

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    Oh sorry! Just found the chart! Says 50 degrees F. should have between 3.25 and 4.15K ohms. So I'm good. It was about 33 out when I pushed it in, and it was only in the shop about a half hour before the test. So it was still kind of chilly! Think I need an ECU and ANOTHER set of plugs! UGH.
    JR.

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    Update! Finally some progress! Firstly, Merry Christmas to all. Hope everyone had a healthy, Happy one.
    Many Thanks to Lenny for the ECU. We have a running car!!! Sounded pretty damn strong, ran up to temp, and right before I got to play with some timing.....Blew a coolant hose! Lol. Not surprised... Just ran out of small clamps at the end of the day. I'll fix that Monday. Was feeling like the timing was funky, Idle too high, when it did go low it sounded like it was misfiring. So I still got some work to do. NBD. Just glad to hear it actually run! I was beginning to wonder.
    Funny quick story...One of the many Fed Ex persons was here and wanted to check out the cars out front. I say sure. There's a 68 GTX and a 72 Road runner, and the Z. He goes right to the Z and starts laughing and carrying on. Turns out he bought this car in 1979 in Arizona!! Drove it out here in 84! Sold it in the late 80's To someone else. My customer bought it 3 years ago from someone who had it for like 7 years and hardly used it. So there's still a big gap in time of what this little Z has been through. It is far from the super nice "Western" car that the Fed Ex guy described! This car is rough!
    Good news is he says it has the bottom end from an 81 so higher Compression. Also the 5 speed from the 81!! I had no idea cause I've never driven the car. So, once I get it running right, get the clutch and brakes functioning, It'll be great to drive!! Sorry this was so long!! Thanks again Lenny!! JR.

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    JR, now you have to post some pics! Don't loose contact with that FEDX guy, he can answer questions that you have and may save you a lot of time.
    1970 240Z HLS30 01955 March/70

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    Quote Originally Posted by grannyknot View Post
    JR, now you have to post some pics! Don't loose contact with that FEDX guy, he can answer questions that you have and may save you a lot of time.
    Lets see if I can do this....HMMM I downloaded a pic.... How do I get it here? Wait, it's in attachments...Ha! got it! See it is definitely not a cherry western car anymore! after I have it running and driving right I still have a bit of sub frame to put under it...lol

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    JR

    GREAT news! I missed your call yesterday & got tied up with family and was hoping you were calling with good news. So the new plugs helped out after the new ECU was in?

    Lenny
    77 280z - test vehicle
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    Yeah Lenny, as soon as I hit the key with fresh plugs it fired right over! Idled way high, My air bleed was cranked wide open. Settled the idle by bringing that way in, was just about to play with timing when the coolant hose blew. Still lots to tune I think. when the idle was low it kept trying to drop out some cylinders ( Like a miss fire) Give it a little gas and it came right back. Funny when it does that it sounds like The exhaust opens up close to the engine...I have some exhaust leaks so they must just be more audible with the miss...? What little I saw of the timing looked like it was pretty far out so that'll require some messing with. That Fed Ex guy said he had to lighten the weights in the dist. to get the advance in later because of detonation. I want to make sure I get that right..Detonation is a killer!
    Going to play with it some this morning. Short day today though. It's my wife's birthday, And I still have another car on my lift that's been there for too long with barely an end in sight! No complaints. Thanks again though Lenny. I'll get both ECU's in the mail to you before the end of the week. If I'm having trouble dialing it in I may be calling...
    JR.

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    Great. Sounds like you're finally making some progress. I'm glad the spare ECUs I have lying around helped out.

    Lenny
    77 280z - test vehicle
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    I think my Reman dist.'s F'D!! Can't time it no matter what. Won't run for crap below 2K RPM's and the it's pinging to beat the band!.... pulled the new dist. out, all the screws holding the pick ups in have grit in them and I keep finding "Media" floating around inside. The Vac advance is bound up. don't want to take it all the way apart. I want to try to send it back....Advance has another coming Thursday. $60 cheaper than Z car source. Really don't have a lot of hair left to pull out so this better work!

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    Something to think about since you are replacing the distributor anyway: You can get a remanufactured 280ZX distributor which includes the ignition module from Rock Auto for $90 and a new OEM coil that goes with it for another $15. The conversion is dead easy. In a nutshell:

    1. Discard/disconnect the old ignition module, coil, and ballast
    2. Install in the new distributor and coil
    3. Connect two wires from distributor to coil
    4. Connect EFI sensor wire/tach (blue wire) to negative side of new coil
    5. Connect two 12V wires (black/white stripe) to positive side
    6. Profit!

    Full instructions are here

    Not sure if it has come up in this thread but does the tach work in this car? Mine was very jumpy and sometimes just didn't work at all. It turns out that this behavior is related to ignition module problems on this car (and they seem to be common problems).

    There is also a related discussion here which ends, for now, how I started this posting and includes the part number.

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    Quote Originally Posted by JRSGTS View Post
    I think my Reman dist.'s F'D!! Can't time it no matter what.
    Is this the Z Car Source distributor? Good to know for future customers. They're going to give a refund, right?

    As far as timing, if the engine is running you should be able to set static timing. The vacuum advance should be on ported vacuum and the idle speed should be below the start of centrifugal advance so nothing should be changing at idle. If you had bad springs and an advance weight flopping around you might get jumpy timing though. You'd have to pop the breaker plate out to see that.

    On the ZX distributor swap - it is simple to do but if your customer wants to retain the car's original functionality you'll need to stick with the stock ignition module and distributor. 1976 Federal models have two pickups in the distributor and two circuits in the module, to bump timing up when the engine is cold. I don't have it on mine anymore and barely notice a difference but it can result in about a minute of lower than normal idle speed while warming up.
    1976 280Z, with some minor modifications

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    sscanf, Thanks for the info. Really cool swap. I already have a reman. coming from Advance For not much more than the Rock one...I'll try it. The one from Z car was WAY more. If it doesn't solve everything, I might just do the conversion to rule out module problems.
    Zed, Nah No originality issues about this ride.. Have ya seen the picture? If it keeps behaving this way it just might get small blocked!! Just kidding.. As far as timing goes, I Can static time it NP. It revs like crazy on start up and if allowed to idle below 1500 it starts dropping out cylinders...Sounds like a tractor...Crappy previous mechanics exhaust work. My vac. pump is broken but if I suck on the adv. can's hose I can't move the adv. mechanism. Not very scientific I know. With the car running I can't even find the timing mark. Looks like it's somewhere WAY ATDC....If I bring it anywhere near spec. It falls to crap. If the new dist. fixes it I'll talk to Z car. I doubt they'll give a refund though. No one stands behind there crap any more.
    I'd be happy with store credit, but we'll see...I'll keep you posted.

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    I've always thought of "static" as meaning no advance mechanisms in play. Basically idle timing. Maybe I misunderstand the terminology.

    Anyway, if the car runs and you have the timing light connected to the #1 cylinder wire and you're getting a steady light just in the wrong place, it won't matter which distributor you have installed. The timing light just tells you when the spark happens in relation to cylinder position. The engine will run the same way at idle with any distributor and module that's producing spark.

    These engines will run, sounding like tractor engines, if the spark plug wires are installed in reverse rotation order. Backward. Worth a double check. They probably like different timing in reverse also.

    At least it's running well enough to know that you have a timing problem. You've made it quite a way from "fuel pump help".
    1976 280Z, with some minor modifications

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    OK, I call Static timing as when you set the engine to TDC and rotate DIST. till we see a spark on #1. Gives a base line to fire the engine..
    I have firing order at 153624 counter clockwise on the dist. At idle I have the timing running way to retarded. Timing mark is way up near the top of the pulley. When I rotate the dist. towards the timing marks it runs like crap and drops cylinders...I was thinking it was bad calibration in the dist. What else could be messing me up? Above 2K rpm's it sounds pretty good, but if you rev it, it will spark knock like crazy...

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    It sounds like your timing marks are not aligned with the #1 piston being at top center on the compression stroke. That's what you should check next. The timing flashes aren't worth anything if the marks aren't correct. If I was in your shoes I would pull the valve cover, rotate the engine until the #1 cylinder cam lobes come up (compression stroke), and stop when the timing mark on the damper pulley is at zero on the indicator.

    Then see how close the timing sprocket notch is to the oblong groove on the camshaft retaining plate. If they are aligned, you could assume that the timing mark is within about 8 degree of correct.

    Whatever the reason that the timing flashes that you're seeing are not working with the marks and indicator, a new distributor will have the same issue.

    I've also seen my timing light pick up the next wire over's pulses. But your problem sounds more like a bad damper or screwed up timing marks.


    OR, considering that it's not your car and have no idea what's been done to the engine, and this statement, "Good news is he says it has the bottom end from an 81 so higher Compression.", it might just be that somebody has built an old-school 12:1 CR "race" engine and it will never run with standard timing. Overall, it might just be time to check the basics of the engine; cylinder pressure, confirm correct timing marks, check camshaft timing (notch and groove), etc., to see how much farther you can go.
    1976 280Z, with some minor modifications

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    I don't know whether it's a potential issue with Z's, but I've heard of some old cars (e.g. Miatas) having issues with the harmonic balancers deteriorating, such that the timing mark randomly shifts. Have you verified that the timing mark really is TDC? Also have you pulled the valve cover and verified the valve train is aligned correctly to TDC? Just a tooth off can cause pretty crappy running. Also the distributor might be a tooth off, so that the rotor only aligns to the correct plug when the timing is retarded. Advance the timing enough, and the spark skips to the next plug, hence cylinders starting to drop out.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    Ha! Zed beat me to it! (I had walked away from my computer. I don't type quite that slowly!)
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    All great info Guys( and Lady) When I "static" Time any engine. I pull #1 plug, Bump the motor over with a switch till it pops my finger off the hole. That way I know it's comp. stroke. The mark is always close, Just a matter of moving it a bit to line up with zero. Then I get spark and fire it over. I'll have to pull the VC to verify Cam position. I need to know it, but I still really feel like this dist. isn't right. I'll get a better look at the balancer. Well aware of slip issues with some cars. Because the mark is so close when I bump it, I'm thinking it's ok. According to the PO. it's not a 12:1 engine, but it is about 10.5:1. So I warned the owner we'll either have to recurve the dist. ( Not my forte) or run octane booster and high test.
    As you said Zed, and I know. The dist. just fires the spark when it spins by the plug tower in the cap. But if the cent. advance is locked up or flopping and the vac. advance isn't working. It's going to make things run like doo doo...No... I felt a lot of grit under the screws when I was checking air gap and trying to get to the cent. weights. I decided not to go too deep in case I'm trying to return it. But things didn't look right in there.
    Started a motor swap on another dead one today. Not sure I'll get to try the new dist. tomorrow. I'll let ya know when I do .
    Thanks for all the input! JR.

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    They sent the wrong Dist. last week...ugh..Way too busy with frozen pipes, messed up furnaces, Shoveling out. Now it's 50 degrees and about to drop below zero again tonight.
    They got me the single pick up dist. If they can't get the right one, I might have to do the GM Module conversion.
    Have to fix my own furnace today and help my Mother in law with her frozen pipes.....Maybe this car will be fixed in the spring...

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    JR,

    I'm not 100% sure, but I believe the single pickup disty will work. The second pickup I think is only used on CA models perhaps??? The two pickups are some fixed degrees apart (maybe 6 or so) & the ignition module decides which one to use . Sorry for the vague info. I've not looked at the ignition circuits in a while. Others here will be way more up on that than me at this point. Hopefully, they will chime in.

    Good luck with the weather & stay warm.

    Len
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    HellFire L28 digital ECU replacement janitor.

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    Post #71 and 72 kind of covered the dual pickup issue. The stock ignition module will work fine with one pickup, it just won't use the other ignition circuit. If you convert to a GM HEI module, you will only be able to use one pickup. In #72 I got the impression it didn't matter anyway.
    1976 280Z, with some minor modifications

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    Newbie here on sight, starting reading, then jumped to bottom.....didn't feel like reading all that, but I take it ...it still don't start. ? Where in upstate? btw Has anyone mentioned the fuel pump contact inside the AFM? I think this is the year, not sure, but that one stumped me once.....on a 280z. Paul, from ctzcc but live in RI (go to NY a lot) (like next week) (got parts as well)

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    Thanks Len and Zed! I was thinking about trying this Dis. Now I will!! according to the Chiltons the owner provided. The Federal has dual pick ups, the CA. has the one...Seems backwards to me. Who cares as long as it runs. I still have to pull the V.C. to check Cam position, but I will.
    Paul, Yeah you needed to read my exceedingly long thread cause we've(thanks to all the great people here) been down the AFM road and all the others too. Car runs good above 2K RPM's Can't get the timing right. Where in NY do you go Paul?

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    Default Happy Dance!!

    IT LIVES!!!! Runs awesome!!! FINALLY!!!! The dist. was F'd.. The new one even being a single pick up fixed everything! Well the exhaust still sounds like crap but.. I'm able to put the timing any where I want it, The motor sounds solid. Sounds like it wants to fly really. Still have a bit high of an idle. 1150 is about as low as I can get it. Played with the idle air bleed, I can shut it right down and it still won't go any lower. Checked for vac. leaks, Nothing. Can't drive it till I change the rear wheel cyl's and shoes or it will grind up a drum. The snow all just melted, so a good window to take it out for a rip..Have to finish one in front of it though so it'll be a couple days.
    Thank you again everyone who helped!!! Lenny, the other ECU will be in the mail tomorrow. Sorry I didn't get it out sooner...Weather BS put me back a bit.. I'll keep ya'll posted on how the first drive goes!!
    JR.

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    Congratulations! Now tell us honestly, don't you think that EFI L28 is a sweet engine?
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    Thank you Sarah I honestly do think this is a sweet little motor! It should be especially nice with the later bottom end. After all, I am a sucker for a nice bottom end! . After I sort out the brakes..and exhaust, I can finally drive it. I may have to bleed the clutch also. THEN I'll report how much fun it is! Hopefully it won't be a ping monster as the PO described. Any easy suggestions for exhaust? I'll search here so not to go off topic.
    Now to see if Z car source will take back the other distributor...

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    Quote Originally Posted by JRSGTS View Post
    I am actually working on this 1976 280Z for a customer of mine.
    I'm a little confused here... Who actually owns this car?

    You sure seem emotionally attached at this point!

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    Motor Sport Auto premium exhaust with a Magnaflow 4" midpipe muffler nestled neatly in the tunnel.

    Motorsport! 70-78 Premium Exhaust - The Z Store, Nissan-Datsun 240Z-260Z-280Z-280ZX-300ZX(Z31/Z32)-350Z-370Z Parts

    A bit of a rumble at idle, but not uncivilized. It doesn't sound at all like some tooner kid's Honda.

    It does sound like the Z is endearing itself to you. They do that. My '75 280 was my first EFI car, and I thought all the Rube Goldbergery on the side of the engine (instead of the carbs) was simply awesome. And the chain drive, flat tappet, OHC valve train? Just plain sexy, in a gearhead sort of way. For me, the joy of the Z isn't the performance. My Miata is more nimble, and so many modern cars will leave a stock Z in the dust. (With mods, though, the Z can still fight very respectably.) But there are very few cars that are as sexy as the S30 Z models. And I've always found my Zs (both of them, owned at different periods in my life) a true pleasure to work on. The Z is an easy car to fall in love with.
    Last edited by FastWoman; 01-09-2014 at 08:19 AM.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    It's true I am attached a bit. I do that with all my clients "Baby's" I have to. As we all know our cars are VERY important to us, so I make all of them important to me. This Z and I have been through a lot already, and I plan to see it become a great fun car! Someone else can do the body work though!
    Thank you Sarah for the exhaust link! That's exactly what it needs next! I'll be selling the owner on it next. I'm glad you prefaced it with not sounding like a fart canned tuner car. I hate those. Any good 6 cyl. with the right exhaust can sound awesome. This car really needs a system bad! I'm hopefully going to get some brakes on it today, then let the owner drive it. That will get him excited for the next phase! Although it is snowing again...That's ok, haven't been drifting in a while!! I'll keep ya posted as always! JR.

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    Well, in all fairness I should tell you that the exhaust is a bit noisy on initial warmup -- at idle, when it's blowing sort of hard. But then again, my idle is too low on warmup because of a stuck AAR. Hearing this, my uncle commented, "Needs a muffler!" Of course he's used to cars you can't quite hear running. Otherwise, the exhaust doesn't have any of that obnoxious raspiness under load. It just has a low, chesty rumble at idle that smooths out around 1200'ish RPM and above.

    My intent with this exhaust system was to try the turbo muffler and to replace it if I couldn't live with it. I can live with it, but I'll probably replace it with a conventional muffler next time around. The midpipe muffler is apparently an essential element for taming this system and getting rid of an annoying drone sound at cruising, and it works great. However, if it were available, my preference would be for the OEM-style exhaust -- maybe a tad bigger, but not much.

    I should also mention that the system sometimes needs a bit of tweaking for a proper fit, especially around the transmission. Of course that's where you'll add the midpipe muffler, so you'll be modding the system anyway.
    Last edited by FastWoman; 01-10-2014 at 08:50 AM.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    Sounds like it will sound just right. I love Dyno-max mufflers. Have run them on lots of cars. To be clear...I thought it looked like this system eliminated the mid pipe muffler..? That would be preferable to me. Especially if this engine is as high comp. as the PO says. I say, open it up, let it breathe, to hell with the DB's! Besides, the mid-muffler is shot! I don't want to have to use it. No worries about fitment issues, got that. Do I need to make a replacement pipe?
    I drove it today!! First time! Down the slushy, salty road! ... I can wash it off right in the shop. Ran pretty good. I think we could still do with some injector cleaning/replacement. I've read here to not get the aftermarket inj. I can get them for under $50 each my cost... I think a fresh set would change everything for the better. I have to sell him on that though. Plus the exhaust he has to have. Translates to another grand + for him.... we'll see.. It was fun to drive though!
    I will add a Z to my toy box wish list! For the record it's a long list. The Z will be somewhere in the middle..
    Finally having some fun!! Thank you everyone! JR.

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    The middle muffler is for "drone" or resonance. It's actually called a resonator by some, although I think anti-resonator might be more technically correct. People that have drone hate it.
    1976 280Z, with some minor modifications

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    If free exhaust flow (hang the noise) is what your customer wants, then you don't need the midpipe muffler. That doesn't come with the exhaust kit. That said, the Magnaflow midpipe is a straight turbo muffler and does not restrict exhaust flow. But it certainly makes the exhaust more civilized. We regularly drive my Z between the coast and Richmond. It's a noisy, but otherwise comfortable car. If I had the exhaust drone added to all the road noise, I think that would tip me over the edge. Just saying!

    As I recall, this is the one installed on my car:

    http://www.summitracing.com/parts/mpe-14416/overview/
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    So the kit Needs something there. I like the idea of less drone. My truck did that before I added an H pipe. Much better. Drone is real harsh in a small 2 person cab that's 50% Glass, the rest straight steel. Thanks for the tip Sarah. Going to let the owner drive it, and see how far he wants to go next.. Hopefully he's ready for some real fun with it now.
    I will let you know! JR.

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    Any thoughts on reasonable injector replacements? If the aftermarket ones are no good, what do you suggest? I do have access to a professional cleaner, I was thinking about trying. JR.

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    Default FJ707T Injectors

    My 1976 280Z (which is still a work in progress and not on the road yet but right now I'm just waiting for the salt to leave the road before I register and insure it). When I bought the car, most of the EFI, including the intake manifold and throtle body and all of the exhaust were removed. I decided to set aside the old crusty injectors and install FJ707T (discussed in this thread). I have nothing to compare them to because I never experienced the car running with the old injectors but I can report that the FJ707T work just fine on my motor.

    Some details on my FJ707T install can be found here.

    Also, FYI, I have the MSA 6-1 header and premium exhaust mentioned above (15-6308 - for 6-1 header). I have to say that it is a little loud for me when I stomp on it, but it idles nicely, and pulls like a demon with this set-up. I will probably add a glass pack to tame it a bit.
    Last edited by sscanf; 01-13-2014 at 08:50 AM. Reason: Forgot something

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    I replaced my old (working, but quite elderly) OEM injectors with the Standard Ignition FJ707T, and it ran about the same. (It still had other issues that I corrected.) I've been running those injectors for the past few years with no problem.

    The hazard with the old, cleaned up injectors is that they can leak, which of course makes them dangerous.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    Wow! Those are pricey! 6X165=990 my cost...Doubt he'll do that. Not sure what brand these were I priced from advance. I do know if they give me any problem they will take them back NP. Maybe I'll try the cleaning first to see if it helps. Fired right up today and drove out of the garage fine, but a little lumpy. Taking the owner for a ride tomorrow. We'll see how much he wants to spend..

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    Quote Originally Posted by JRSGTS View Post
    Wow! Those are pricey! 6X165=990 my cost...Doubt he'll do that. Not sure what brand these were I priced from advance. I do know if they give me any problem they will take them back NP. Maybe I'll try the cleaning first to see if it helps. Fired right up today and drove out of the garage fine, but a little lumpy. Taking the owner for a ride tomorrow. We'll see how much he wants to spend..
    I got all six Standard brand FJ707T injectors, including shipping, for $165 in 2012. They seem to be a little more than that now (~$29 each + shipping) but you should be able to do way better than $165 each.

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    Z geek at large FastWoman's Avatar
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    Correction: I have the Standard FJ3 injectors. I had forgotten that sscanf had a different part # than I do. The FJ3 injectors are listed for the 280Z. I can't say whether they differ appreciably from the FJ7. I got mine for $150/set off of ebay. You can find the same deal there now:

    75 76 77 78 79 80 81 82 83 Datsun 280z Fuel Injectors | eBay

    The only incompatibility I found was that the hoses were about 3/4" too short. So I cut them off and clamped on longer hoses (pretty easy).
    Last edited by FastWoman; 01-13-2014 at 11:30 PM.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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