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94 gmc 2500 won't start

Discussion in 'Truck & Equipment Repair' started by chev2500plow, Mar 21, 2009.

  1. chev2500plow

    chev2500plow Member
    Messages: 40

    I have fuel pressure and spark but it just turns over, if i dump gas in throttle body it will start. I replaced coil and ignition module still nothing. Any ideas or help would be great thank you.
     
  2. CARDOCTOR

    CARDOCTOR PlowSite.com Addict
    Messages: 1,310

    how do you know you have enough fuel pressure. can you hear the pump run.

    JR
     
  3. chev2500plow

    chev2500plow Member
    Messages: 40

    i put a pressure guage on it and made the pump run by putting a wire from the battery to the diagnostic port under dash, and it had 14psi.
     
  4. mikeyfff1011

    mikeyfff1011 Member
    Messages: 72

    sounds like the pump if its running when you spray down the throttle body it wont run if it doesnt have the right fuel pressure
     
  5. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    But are the injectors clicking when you have it running on the forced fuel? I'll bet not... so it needs a fresh pickup coil. Yes I know you said you have spark, but with a bad PU coil you can still have spark but no injector activity...see it all the time on the TBI stuff.

    But do yourself a favor and just replace the distributor as a whole. Until you purchase a replacement PU coil and attempt to install it you'll be happier in the the end to replace it all.
     
  6. CARDOCTOR

    CARDOCTOR PlowSite.com Addict
    Messages: 1,310

    get a noid light unplug harness at injector .plug in noid light crank see if it blinks . if it doesnt
    koeo one of the wires should have 12 volts. 14 psi sound low dont have specs infront of me

    JR
     
  7. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    14 psi is actually at the high end of the spec of 11-14 psi...most won't even make more than 12...
     
  8. CARDOCTOR

    CARDOCTOR PlowSite.com Addict
    Messages: 1,310

    i m so use to mpi injection

    JR
     
  9. Mike N

    Mike N Senior Member
    Messages: 148

    Sounds more like the module than the pickup coil. If you have spark the pickup is good.

    Another thing to check is the tps. Make sure it's not stuck at 5 volts and putting the truck into clear flood mode.
     
  10. chev2500plow

    chev2500plow Member
    Messages: 40

    Replaced distributor still nothing. when i turn key forward shouldn't the fuel pump prime, because mine doesn't. thank you
     
  11. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    I've had many many in the past that would have enough spark to physically run but not enough (ie sustained) signal from a failing PU coil to actually trigger the injectors in secession.
     
  12. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Did you even check first for injector response like I mentioned before changing the dist? Sounds like not...


    What procedure did you use to check and identify proper fuel press when the fuel pump doesn't even run? Did you check it static or while cranking? Makes a difference....

    Attach a fused 12V jumper wire to the fuel pump prime connector and see if you get pump function.
     
  13. mikeyfff1011

    mikeyfff1011 Member
    Messages: 72

    its possible you have a bad injector to one could be shorting the other try that..
     
  14. chev2500plow

    chev2500plow Member
    Messages: 40

    No the injectors do not click unless i put power to them. As for the fuel pump i can only get it to run when i jumper it on the diagnostic port under dash.
     
  15. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Time to start checking for power where there should be. Start in the fuse panel looking for blown fuses and also the fusable links for rot/corrosion. Have to start narrowing it down.
     
  16. chev2500plow

    chev2500plow Member
    Messages: 40

    I already checked all fuses in fuse panel all good. checked fuses where fuel pump relay is power on both sides of fuse. i'm hoping it's not a broken wire some where. thank you
     
  17. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Don't forget the grounds too. There's one on the T-stat housing (ECM ground) and one or two on the rear of the pass side cylinder head.