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Odd TBI issues

Discussion in 'Engine & Performance' started by Cydways, Mar 6, 2021.

  1. Cydways

    Cydways Junior Member

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    Truck Year:
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    Truck Model:
    V2500 Suburban
    Engine Size:
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    1990 Suburban 5.7 TBI. I had been having problems with the truck idling high and running poorly, found out the throttle body gasket was bad. So bad, it had a huge chunk missing when I pulled it off.

    So I decided to rebuild the throttle body. Put it back on and now the engine cranks but will not fire. There is no injector pulse. The fuel pump does not prime when I turn the key, but it will run when cranking and for a couple seconds after cranking.

    I checked the TPS because I heard that can prevent the injectors from firing if it's broken. There is no voltage at all - no power going to it and thus no voltage at the blue wire.

    I am at a loss. If the fuel pump does run, even though it does not 'prime,' shouldn't the relay be good?

    What would prevent power from going to the TPS?
     
  2. Cydways

    Cydways Junior Member

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    I forgot to mention, the engine does have spark, it will fire up with a little ether.

    Also the fuel pump does not run until the oil pressure builds from cranking.

    Also all the fuses are good.
     
  3. Vbb199

    Vbb199 B-rate Hillbilly Customs

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    Fuel pump needs replaced probably.
     
  4. Cydways

    Cydways Junior Member

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    The fuel pump is brand new
     
  5. gmbellew

    gmbellew Full Access Member

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    check the plug wires to make sure you got them back in the right order and check to make sure you got all the ICM connectors solid. if it ran before, I would suspect that something got put back wrong.
     
  6. 85Sierra Classy

    85Sierra Classy Junior Member

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    Check ECM fuses. Also no fuel pump prime is usually caused by bad fuel pump relay, very common with TBI trucks. The pump will run when the oil pressure builds regardless of the condition of the relay
     
    bucket and CorvairGeek like this.
  7. Cydways

    Cydways Junior Member

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    Well I feel like a horses arse and I apologize for having created yet another 'tbi issues' thread.

    ECM fuse was popped. Thank you 85Sierra for reminding me to check them again.
     
  8. 85Sierra Classy

    85Sierra Classy Junior Member

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    It happens to the best of us! Glad you got it sorted out.
     
  9. 45acp

    45acp Member

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    X2 on the thank you! I just learned something.
     

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