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Injector Wire Pulsing

Discussion in 'The Garage' started by stockk5, Sep 5, 2006.

  1. stockk5

    stockk5 1/2 ton status Premium Member

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    Hey, im trying to figure out why my injector wires for my tbi arent pulsing. The computer is good, the computer is getting power, its just the injectors are pulsing at all. Does anyone know if there is a fuseable link somewhere from the tbi injector wires to the computer or something inbetween? I think the problem started when i made my own heat shield for the starter which in turn i think shorted something out. Everything has power, and the carb is getting gas.. but its not shooting the gas in the carb because the injectors arent pulsing. Sry for so many post on this stuff..i just try something new everyday trying to break it down piece by piece.
     
  2. readymix

    readymix 3/4 ton status

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    One side of the injectors is supplied with a constant 12Vdc
    The other side is "switched" to ground allowing the injectors to fire.

    Don't look for the pulse on the hot side, you will never find it.

    If you already knew about what I just typed then you are on the right track. The pick-up could and ignition module will both cause the injectors to not fire. Are you getting spark to the plugs? Check that first, then we will be able to help more.
     
  3. stockk5

    stockk5 1/2 ton status Premium Member

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    its getting spark to all the plugs and when u spray carb cleaner into the carborator it starts the truck up and runs off the fumes so its getting the sparks but not getting the fuel. and the ignition module is good i tested that already.
     
  4. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

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    Is it tossing out any trouble codes?
     
  5. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    The only other thing that I can think of other than a faulty ECM that can cause your injectors not to fire if the ECM is infact receiving the DRP signal from the ignition module (as proven by the fuel pump running when the distributer fires), and your injector wiring is good (12 volts with ignition on one pole, nothing on the other) is a TPS that is at above 75% throttle while cranking...

    It is set up so that if you somehow manage to flood your TBI, you can keep the injectors from pulsing while cranking the engine, much like holding the throttle wide open on a carb, except a bit more effective...

    Check your TPS voltage, and make sure that it is sitting at about .54 volts at an idle.

    If that all fails, figure out what shorted out in your injector wiring, check your ECM grounds, then replace the ECM as the injector drivers must be burnt up...
     
  6. stockk5

    stockk5 1/2 ton status Premium Member

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    well i actually took the computer from my bros k5 an 89 w/ a 350 and then plugged it into mine. Still didnt work, thats how i determined it wasnt the computer. The tps is the throttle possition sensor correct? Also where would the ECM grounds be. the ECM is the silver computer box in the dash behind the glove box.. just want to make sure we are talking of the same thing.
     
  7. CB77GMC

    CB77GMC 1/2 ton status GMOTM Winner

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