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Tech Question: Noangel's 88 intermittent start problems

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Leadfoot, Aug 5, 2002.

  1. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Tech Question: Noangel\'s 88 intermittent start problems

    Noangel returned from vacation this past weekend and we decided to do some work on her blazer. The blazer intermittently starts (usually, but not always likes to start when cold or sitting), but if you shut if off and try to restart it, it just keeps cranking. I replaced the ignition module with a brand new one (smeard the dialectric blue grease all over the bottom and installed per instructions). The thing fired right up (but had been sitting). She parked it, shut it off and tried to restart it, and it just kept cranking. Any thoughts guys/gals? I'm thinking maybe the coil or computer, but I'm new to the TBI world so I am clueless.

    Any suggestions?
     
  2. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    Could be the in-tank fuel pump. I had an S-10 with a similar problem.... Turned out to be the pump.

    Hope it helps,
    John
     
  3. Calclips

    Calclips 1/2 ton status

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    Have somebody lay under the truck when you turn the key forward, and they should hear that fuel pump kick on. It'll make a whirrring noise for a second or two. If you hear that I'd try and replace the fuel filter. If you still have a problem with it starting, then I'd pull a fuel line off the TBI and see if you have gas coming out. If you have gas at the TBI unit then you know where to start looking for the problem for sure. Oh, by the way, when you take the air filter off and look down the TBI while somebody cranks it over, do the injectors spray two nice even cones of gas? if they don't then they are the problem.
     
  4. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    When it does start the spray pattern isn't the best, but it sprays. When it doesn't start there is no spray whatsoever. I don't think it's the pump (but who knows). Is it designed to shut off at a certain PSI? Also, I have heard oil pressure controls the pump (no pressure no fuel). Is the same true for coil spark. I know if the module is bad the injectors will not spray, but is the same true for the coil? Also what about the computer. Does the 88 have an ECM, and if so where is it located? Any way to test it?
     
  5. Calclips

    Calclips 1/2 ton status

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    Whoah! You just blew past my level of knowledge on this subject. I've told you pretty much everything I know, I know it all because I had to do it on my truck... but I only had to go in as far as the ignition module and then it was fixed. I wish I could be of more help, but now I don't know.
     
  6. jc71355

    jc71355 1/2 ton status

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    88 Has a computer and it should be behind the glove box. I believe that the pump only goes on oil pressure when the fuse for the pump is bad. Have you been getting the check engine light on? If so check the code's and see what they tell you. I don't know of a way of checking the ECM. Have you tried the fuel filter? Just a thought. The pump will come on when you turn the key on just to prime the system then it will shut off. Hope this helps.
     
  7. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    No check engine light so I don't think it will show any codes. Question: Will any and all codes cause the check engine light to come on? Supposedly the fuel filter was replaced, but I am going to do it again. Does anyone know where it is located on these rigs? Also is the fuel pump in the tank?
     
  8. Scooter

    Scooter 1/2 ton status

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    On my 87, the fuel filter is in the passenger side frame. The fuel pump should be in the tank. Good luck with replacing it. When mine went out, instead of dropping the tank, I just cut a U shaped section of the floor and folded it out of the way.
     
  9. jc71355

    jc71355 1/2 ton status

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    Fuel pump's in the tank. Fuel filter is on the passenger side frame rail right behind the T-case.
     
  10. TopOff

    TopOff 1/2 ton status

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    Just a thought...The pump will shut off if it doesn't get a signal from the distributor... So if the connections from the distributor are bad, the computer might think it is not cranking.. hence, no fuel.

    Good luck.
     
  11. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    Thanks everyone for the input. I will be checking several of these items in the next week or two and post my findings.
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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  13. alec78

    alec78 1/2 ton status

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    The injectors are actually driven by a signal from the distrubitor pickup via the ECM. If the pickup coil (the yellowish round thing under the rotor) is bad it will usually show signs when it is hot. The fuel pump automatically runs for about 15 seconds of the key being turned on then it looks for the distributor signal (same one as the injectors). There are a lot of other weird factors that can keep the injectors from operating but this is the starting point.
     
  14. newyorkin

    newyorkin 1 ton status

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    There's a test jumper connection you can make to verify the fuel pump turns on when it has power, somewhere on the aldl connector under the dash. I don't remember which terminals, maybe someone else here does? I have the book home, I can look it up later if you want.
    THe fuel pump will come on when you turn the key on initially, but it won't come on again for I think 5 seconds. So if you flip the key on then off then on then off in under 5 seconds, only expect to hear the pump cycle once, and then I beleive you need turn it off, wait five seconds, then try again.

    I did two in-tank pumps on K5's. I don't remember them being too bad of a job at all. Enough so, that I've been thinking of changing mine before it fails, because it's so damn noisy (could also be another botched previous owner job)...
     
  15. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    If you could get that info it would be appreciated, I'm sure it will come in handy for others as well (that's the type of thing I put a reminder on).
     
  16. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    I can't upload the pic to my site from where I am now, anyone willing to host the pic if I email it to them?

    BTW, the Camaro wiring diagram I posted SHOWS the ALDL connector for the fuel pump.
     
  17. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    Alright heres the pinout. (got lucky and the transfer worked) Yes this works on various GM vehicles, but all the wires should be in exactly the same position, but based on year, some will be present and some won't.

    http://www.dorianyeager.com/TablePics/ALDL.gif
     
  18. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    Sweet!
    Thanks Dude.
     
  19. Twiz

    Twiz 1/2 ton status

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    Re: Tech Question: Noangel\'s 88 intermittent start problems

    I posted this on the old thread- didja loose it?

    1- Turn the key to "on", can you hear the in-tank fuel pump? It should run for about a 2 secconds then turn off.
    2- Crank the engine, can you hear the fuel pump now? The fuel pump should stay running as long as the ECM is receiveing a dist. signal.
    3- Keep cranking, and watch the engine oil pressure gage if equiped (hopefully). Does the engine start and run when the engine oil pressure comes-around? The engine oil pressure switch is a "back-up" system, when it senses oil pressure it turns-on the fuel pump. (by-passing the fuel-pump relay)
    4- If the fuel-pump never turns on. Hit the fuel tank with a hammer, while someone holds the ignition switch in the "crank" position. This might free-up the fuel pump enough to start and run. (if this is the case, the fuel pump is bad)
    5- If possible, check the fuel pressure. (doesn't sound like this is applicable here tho')

    If the fuel pump sys. does not perform as stated above, what step did it fail to perform correctly? (will help in diagnoseing the problem)

    Now, if the fuel pump sys. appears to be working correctly.
    The next logical step would be to check for spark/ignition.
     

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