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  1. #1
    Junior Member Registered Member
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    No Fuel out of Injectors

    1990 GMC 350 throttle body.
    Getting fuel to the throttle body but not out of the injectors.
    Pressure "looks" good but do not have a pressure guage to confirm.
    I have replaced the computer "brain" and what i think is called the "pick-up" coil that
    is inside the distributor.
    I am off to purchase a noid light to see if they are pulsing?
    Please Help!

  2. #2
    Junior Member Registered Member
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    Noid light confirms nothing happening!
    No steady light or pulsing light at the noid light when the key is turned on or cranking!
    I am at a loss as to what to do or try next.
    ANY suggestions are greatly appreciated!

  3. #3
    Spam Reaper Site Moderator Slanter's Avatar
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    Ok, trace this backwards. You'll need a wiring diagram. Do you have an analog multimeter? Next to an oscillascope, it's probably the best tool for this job. You can use a digital multimeter if you don't have an analog, and a 12V test light might work if not. I'm not sure a timing light is the right tool for the job here - I presume that's what you mean by a "noid light." Correct me if I'm wrong there.

    After verifying that the injector is not getting a signal, follow the wire back to where it comes from on the computer. If the signal is leaving the computer, there's a break in the wire or a short somewhere. If the computer isn't signalling the injector to fire, check the input signals to the computer.

    Good luck.
    Slanter - redefining "jury rigged repair" since 1997
    '66 Dodge Dart & 2000 Ford Focus -
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  4. #4
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    Thanks for your help. A "Noid Light" is a hand little device you can buy at the autopart store that plugs into the wire slug that would plug into the injector. As you turn the motor over with the noid light plugged in it should pulse. My noid light is not pulsing, confirming it is not getting it's signal to fire. I will consider what you told me. Do you know the best way to get a wireing diagram? Manuals i have aren't detailed enough, i would love it if i could find something online. Thanks again.

  5. #5
    Spam Reaper Site Moderator Slanter's Avatar
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    Ok, that sounds like the right tool for the job. Wiring diagrams are hard to find on the Internet; your best bet if you want a download is to find a TBI enthusiast site. Often the best wiring diagrams are ones you find in print, in the manual that the factory issues to its service techs.
    Slanter - redefining "jury rigged repair" since 1997
    '66 Dodge Dart & 2000 Ford Focus -
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  6. #6
    Gm Dealer Tech Registered Member
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    Quote Originally Posted by JWboing
    Noid light confirms nothing happening!
    No steady light or pulsing light at the noid light when the key is turned on or cranking!
    I am at a loss as to what to do or try next.
    ANY suggestions are greatly appreciated!
    i would check to see if any spark is happening at the same time as no injector pulse, if you dont have any spark i would say that the ignition module is bad, but by sure to check all the wiring from the pick up coil to the module

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