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Thread: 280Z has issues staying running

  1. #1
    Registered User FlameThrower's Avatar
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    Default 280Z has issues staying running

    My first drive of the year didn't go as well as I had planned.

    The car fired up fine on the first crank although it did feel a bit rougher than I remember from last summer. took it outside to idle for a bit to let the battery charge and it barely had the power to drive out of the garage because it was running so rough.

    If i let the car idle on its own it will just stumble and die, it wont run unless i keep my foot in it. Judging by the exhaust i think it is burning oil too.

    I have checked the basics like the ignition system and the fluids, they all look fine.

    As far as i know this motor has never been pulled apart and rebuilt, does it sound like it is finally time?
    '76 280Z 7/76

  2. #2
    Registered User cozye's Avatar
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    not so fast. Sounds like it's running rich. Perform diagnostic on fuel system, I would start with the water temp sensor, cold start valve, and thermotime switch. the motor doesn't die from just sitting all winter. More than likely something in your fuel injection system has gone bad. Full diagnostic procedure is in the FSM, you can do it with an ohm meter.
    1978 280z 4sp

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    Registered User FlameThrower's Avatar
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    Thank you so much for the suggestions, it turns out the cold start valve was not working properly, it would not close. I swapped it with the one in my parts car after i cleaned it out and it fired right up and ran properly.

    Also noticed that i have a leaking fuel injector. It looks cracked along the side of the body. Any tip on where to find a set of 6 for cheap??

    Thanks again!
    '76 280Z 7/76

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    Registered User cozye's Avatar
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    no such thing as good cheap injectors. I just had all 6 of mine serviced, flow tested and "refurbished". However one of mine must still be leaking as I'm still having the hot start issue occasionally and I've ruled out all other sources of leaks in my fuel system, so one ore more are still leaking. I just bought 6 new ones from MSA for about $300. I wish i wouldn't have spent the $100 to test and "refurbish" mine.
    1978 280z 4sp

  5. #5
    Z geek at large FastWoman's Avatar
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    I was told by my local Z specialist not to buy refurbed injectors. I asked which new ones I should buy, and he said it didn't really make a whole lot of difference, as long as they're new. Trusting in his advice, I bought a set of Standard Ignition injectors off of Ebay for about $150, and so far they're doing great:

    http://cgi.ebay.com/ebaymotors/75-76...Q5fAccessories

    The only thing about these injectors is that the pigtails are a bit too short. Plan on removing them and clamping on some longer pigtails. I probably could have reused the ring-type connectors, but I didn't fully trust them. I just used conventional clamps instead. Very easy.
    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 )

  6. #6
    Registered User Willoughby Z's Avatar
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    Quote Originally Posted by FastWoman View Post
    I was told by my local Z specialist not to buy refurbed injectors. I asked which new ones I should buy, and he said it didn't really make a whole lot of difference, as long as they're new. Trusting in his advice, I bought a set of Standard Ignition injectors off of Ebay for about $150, and so far they're doing great:

    http://cgi.ebay.com/ebaymotors/75-76...Q5fAccessories

    The only thing about these injectors is that the pigtails are a bit too short. Plan on removing them and clamping on some longer pigtails. I probably could have reused the ring-type connectors, but I didn't fully trust them. I just used conventional clamps instead. Very easy.
    Good morning,
    I am considering these injectors: can you explain further, regarding the pigtails? Also your comment about the ring-type connectors vs, th clamps?
    Thanks

    HLS30 371-239 (1/77)
    Every time he touched her, she told him that places where she wanted to be more beautiful!
    Mr.Tamura said it is like an old craftsman of Buddha statue,he did not creat it, Buddha itself...
    Kats

    FSM: http://www.xenons30.com/reference.html
    EFI "bible" : http://www.4moores.com/280z/files/280zfuelinjectionbook.pdf

  7. #7
    Z geek at large FastWoman's Avatar
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    By the pigtails, I mean the little hoses. As I recall they're about an inch too short. What you have to do is CAREFULLY slit the rubber around the injector barbs, cutting at an angle that would just graze the soft aluminum barb, not scratch it (or else you'll have a leak). You should actually only cut deeply enough to slice through the cloth reinforcement, but not through the inner layer of hose. Then you can peel the hose off of the barb and out of the little end-cup/cap that's used to secure it. You can put on another fuel-injection rated hose with a regular clamp around the barb.

    The cup/cap thingie is an alternative to a clamp. The hose butts into it, and it keeps the hose from backing off. The barb has pretty aggressive ridges to grip the rubber. I suppose you could reuse the cup/cap, as it's not damaged during removal, but I just trust a clamp more than I trust that little thing.

    BTW, I'd pick up the Comp Cam clamps from Summit Racing -- the ones with the smooth inner surfaces that don't eat into the hoses. You can pick up larger clamps of that variety from Hampton Rubber, but they don't have the smaller ones. Or at least they didn't when I was buying mine. Get the ones like these (but pick the right size):

    http://www.summitracing.com/parts/CCA-G3912/
    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 )

  8. #8
    Registered User Willoughby Z's Avatar
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    Thanks for the clarification! I wanted to be certain that your reference to pigtails was not the electrical connectors/wire leads, which I intend to replace during injector replacement. The boots on mine are shot and I would prefer to find the squeeze-type connectors as an upgrade. I appreciate the reminder to use FI hose clamps. I have a similar problem (cozye) with a "hot start". Car starts easily, runs smooth. After reaching operating temp and the engine is shut down for a short time, the idle is rough, stumbling. I rev it a little, keep it from stalling and within a few minutes, the coughing clears up and the car runs fine. Longer shutdowns 30-45 miinutes or longer, there's no issue. There is a fuel pressure gauge mounted on an after market fuel rail that shows 30-32 psi when running. Pressure disapates after a few hours to zero. I'm assuming bad fuel return check valve or leaky injector(s). I have trouble getting the idle to stabilize from one day to the next. It has never liked 800 rpm, seems to prefer 900-950. Some days, all on it's own it may be 1100-1200 (warmed up), then drop to 1000 between stoplights. Every once and a while when coming to a stop, the idle will drop to 600-700 and I can hear the fuel pump relay clicking(?) and it will stall.

    HLS30 371-239 (1/77)
    Every time he touched her, she told him that places where she wanted to be more beautiful!
    Mr.Tamura said it is like an old craftsman of Buddha statue,he did not creat it, Buddha itself...
    Kats

    FSM: http://www.xenons30.com/reference.html
    EFI "bible" : http://www.4moores.com/280z/files/280zfuelinjectionbook.pdf

  9. #9
    Registered User Willoughby Z's Avatar
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    My apologies for hijacking the thread, was in my "diagnostic" mode...

    HLS30 371-239 (1/77)
    Every time he touched her, she told him that places where she wanted to be more beautiful!
    Mr.Tamura said it is like an old craftsman of Buddha statue,he did not creat it, Buddha itself...
    Kats

    FSM: http://www.xenons30.com/reference.html
    EFI "bible" : http://www.4moores.com/280z/files/280zfuelinjectionbook.pdf

  10. #10
    Registered User FlameThrower's Avatar
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    Hey no worries, i was doing some of the exact same research when i started digging into the fuel injection on these cars.

    Thanks for the link on the ebay injectors, im going to pick up a set this weekend, is there anything else i should look at while i have the fuel rail off?
    '76 280Z 7/76

  11. #11
    Z geek at large FastWoman's Avatar
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    Be sure to pick up a set of insulators and O-rings for your injectors!
    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 )

  12. #12
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    I've tried to put the insulators. And it is effective. Thanks for you write up.

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