I Need One Of You Wizards To Help Me With Fuel Injection Problem

Discussion in 'General Chevy & GM Tech Questions' started by tx1tek, Feb 12, 2013.

  1. tx1tek

    tx1tek New Member

    I'm trying to help my son who is back from the service to get his 1990 G20 Van running.
    We have it narrowed down to the injectors not putting fuel into the intake. When we manually squirt fuel in, it starts, then quits when the fuel is spent.

    We have checked and there is 12v power to one side of each injector, and there is fuel pressure also, but it's not getting the negative pulse from the computer. The wiring from the computer to the injectors is good. I purchased a new ignition module and installed it in the distributor. Still nothing.

    We also tried a different computer from the wrecking yard, no go.

    Also, when we ground the negative pulse wires (Dark Green and Dark Blue) at the computer, the injectors shoot fuel into the intake.

    Where does the computer get the signal from to tell the injectors to shoot the fuel?

    Any advice would be greatly appreciated.
    Thanks guys
    Last edited: Feb 12, 2013
  2. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    From the PCM.
    However, the PCM relies upon a number of inputs to tell it what to do.

    It needs to know the engine is running, the temp of the coolant, the engine rpm, etc.

    When first started, the cold engine uses a program table from the PCM to adjust injector duration. as the engine warms, the external sensors take on a larger role.

    I'm guessing, the PCM does not know the ignition is "on".

    Check the PCM fuses, there may be a number of them.

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