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Thread: won't start after rebuild

  1. #1
    Texan saridout's Avatar
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    Default won't start after rebuild

    i just got through a complete rebuild. i tried the first startup, and at first, it seemed like the car wasn't reacting to the key turning, other than the lights coming on. then i could hear a small clunking noise every time i turned the key, coming from under the dash near the fuse box. we ran a wire directly from the battery to the starter, and it turns over like mad, but won't start up. any ideas?

    update: there is definitely fuel coming up at least as high as the fuel lines over the manifolds.
    Last edited by saridout; 10-10-2009 at 06:07 PM. Reason: update
    1976 280z Automatic

    my 280z flickr set

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    Man, where to beging. First, you really are not giving us enough information. What have to done to verify everything was installed correctly, fuel pressure, timing, etc.

    Saying that, it could be anything. Have you:

    1) Verified timing. Are you sure you installed the oil pump shaft correctly? This will cause all sorts of problems if you installed it incorrectly.
    2) Did you mess with any electrical in the car during the rebuild?
    3) Verified fuel pressure. Just because fuel is "coming up at least as high as the fuel lines" does not mean it has adequate pressure.
    4) Verified your injector clips are securely fastened to your injectors.
    5) Verified spark. Are you sure you have getting spark from your distributor?

    This is just the beginning
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    Texan saridout's Avatar
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    1) i thought i had timed the oil pump correctly when i first put it together, but it seemed to be off once i got the distributor back on. i pulled the pump off and we put the engine at top dead center and lined up the rotor with the mark for 1 on the distributor body. as far as i can tell, it's timed.

    2) during the rebuild i did a complete engine bay refresh. pulled everything out forward of the bell housing. i replaced all my injector connectors, the starter/solenoid, a handful of misc wires and connectors such as one of the spade connectors on the ignition resistor. edit: the fusible link coming off the battery seemed to be shot, so i just pulled it out for now and connected those wires together in its absence. i can't imagine that that would cause this.

    3) i will check this in just a bit.

    4) they are fastened as securely as possible.

    5) i'll check this tomorrow.

    until then, do you think that the lack of response to the key and the clunking sound are caused by whatever's keeping the engine from starting? or is one causing the other?
    Last edited by saridout; 10-10-2009 at 08:33 PM.
    1976 280z Automatic

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    Texan saridout's Avatar
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    i checked the oil pump again and took a photo of the rotor (see attached). the engine is definitely at TDC, the lobes for the first cylinder are up, the rotor is lined up with the timing mark. i don't think i could be any more certain that it's timed correctly.

    unfortunately, i can't find my fuel pressure gauge, but i should probably mention that when dad unclamped the top of the hose coming from the fuel filter to the steel fuel lines, it started spewing out from around the end, and the pressure pushed it off and got gas all over him. if this doesn't mean i have adequate pressure, i'll have to wait until i can get back out here next weekend. when i put on the new injector clips, i did my absolute best to get the wires attached exactly as they had been previously, but it's possible i got one or two switched. does it matter if the two white wires going to an injector get switched around?

    i'm definitely getting spark. it really sounds like it wants to start. here's a video: http://www.flickr.com/photos/26373558@N08/4002737936/
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    1976 280z Automatic

    my 280z flickr set

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    Texan saridout's Avatar
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    ok, kind of embarrassing update: after rechecking all the connectors in the engine bay, i noticed that the large plug on the dropping resistor was not fully engaged. after connecting it, the car still wouldn't start with the key, but a wire again from the battery to the starter made it start almost immediately.

    it runs VERY rough, with a heavy lope and dies after about a minute. moving the distributor doesn't seem to make that much of a difference, though at some points, it seems to smooth out for about 10 seconds and then go back to loping again before it dies. found a pressure gauge, and it says i have late valve timing. i'm almost 100% positive that i timed the cam correctly. what else could be causing this reading?
    1976 280z Automatic

    my 280z flickr set

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    The "heavy lope" sounds like you have certain cylinders that aren't firing. Are your plug wires hooked up in the right order? I think it's 153624, but that's just off the top of my head. Make sure you don't have the order backwards!

    When you read the engine vacuum, does the needle jump around in a pattern, or does it stay relatively smooth? Jumping around (very abruptly) would suggest a valve problem.

    Pull your wires one by one to find the cylinders that aren't doing anything. (When you pull a wire from a dead cylinder, the engine won't run any differently.) Hold each wire with a rag when you pull it. When you've identified the dead cylinders, verify that you have spark and fuel to those cylinders. Also verify compression on all the cylinders.
    My last three sports cars while I still owned all three:

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    Supporting Member Diseazd's Avatar
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    Put a timing light on it.......it sounds like your timing(ignition timing) is way off. The timing should be between 10 to 15 degrees before TDC.
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    sorry i haven't responded yet. i can only get out to my car once a week.

    fastwoman: all the spark plug wires are correct. double checked em

    the vacuum gauge stays steadily in Late Valve Timing.

    i did as you said and pulled the injector plugs, and i'm pretty sure they're all ok. one seemed a little suspect to me, but i'm probably imagining things. i'll check it again this weekend. i'll also need to go buy a compression tester cause dad can't find his.

    dad is fairly certain that the engine runs smoothly for the first minute or so, and THEN starts loping. i'll agree it certainly did that the last time we started it, but i can't say if it's done that every time we've started it. it may have only started running smoothly then loping since we timed it.

    diseazd: we timed the engine... it runs smoothest at about 13 before TDC, which isn't saying much. man, it kills me when you comment on my posts, cause then i spend an hour looking at your photos :P
    1976 280z Automatic

    my 280z flickr set

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    Texan saridout's Avatar
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    so i rented a compression gauge from Autozone, and it's consistently telling me that my compression is about 105 on all 6 cylinders. i think there's something wrong with the gauge. what do you think?
    1976 280z Automatic

    my 280z flickr set

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    Quote Originally Posted by saridout View Post
    so i rented a compression gauge from Autozone, and it's consistently telling me that my compression is about 105 on all 6 cylinders. i think there's something wrong with the gauge. what do you think?
    I had this happen with one of my gauges; the schrader valve that is on the inlet side (not the release) was sticking. I replaced the valve and the new values were higher and no longer had the same value for all cylinders. I also confirmed it with a second gauge.

    Al

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    argh, i can't seem to get a gauge that works worth a dang. the second one i've tried seems to be broken, but it gets up to 150. hopefully third gauge is the charm.

    here's a video of the car running from yesterday. it's hard to hear the lope on the audio, it gets worse around the time i start talking.

    http://www.flickr.com/photos/26373558@N08/4048852266/
    Last edited by saridout; 10-26-2009 at 07:29 PM.
    1976 280z Automatic

    my 280z flickr set

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    Texan saridout's Avatar
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    may be of no consequence, but when we rev the engine, it often backfires.
    1976 280z Automatic

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    Texan saridout's Avatar
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    bueller?

    i think i'll repost this under the new problem to get some more responses. thanks everyone!
    1976 280z Automatic

    my 280z flickr set

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    Hello,

    I ran into something like this when i performed my rebuild. I had everything TDC and only to find out that the Distributor was 180 deg out. It is an easy mistake to make. Pull the Distributor out and then set everything back up to #1 TDC (Pull the #1 plug to make sure), now look at the little "Half-Moon" line up on the Distributor and the socket on the engine. Make sure that it is aligned properly, I am betting that this is you issue. I can send you FSM pics to get into more detail if you need.

    -Andrew

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