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Need some TBI help...89 K5 with 350/auto

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Midwestblue, Oct 16, 2004.

  1. Midwestblue

    Midwestblue Registered Member

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    I finally got the motor back into my 89 K5, but now it seems like I'm not getting fuel to the throttle body. It has been sitting for 8 months, not running. I don't know how much gas was in it when it was parked but I put a couple of cans of fuel additive in it and several gallons of new gas and changed the fuel filter.
    I'm thinking either bad fuel pump or clogged line.
    How loud is the fuel pump? I can't really hear anything from the tank when I turn the key.
    I unscrewed one of the lines from the new fuel filter and several ounces of gas leaked out so I'm not sure the pump is bad.
    What would be the best way to clear the fuel line? Can I use air and blow it between the line on the back of the TB and unhook the line before the fuel filter?
    Any other ideas? I'm kinda stuck
    And thank you for the help /forums/images/graemlins/thumb.gif
     
  2. Rolled

    Rolled 1/2 ton status

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    I can't hear mine when I turn the key. I was able to hear it when I had the sending unit out. I guess you could hear the pump if you put your ear up to the tank and had a helper turn the key...

    If you have pressure at the filter, your pump *is* working.
     
  3. Midwestblue

    Midwestblue Registered Member

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    Is there anything else to check besides clogged line?
    If the lines were completely dry, no fuel, how much cranking will it take to get gas back up to the throttle body?
    I ask that because if I prime it, she starts right up and runs until it burns that away and then dies.
    And what does this wire do here on the passenger side of the firewall? I thought it has something to do with the fuel pump but I can't find the other end of the connection
    [​IMG]
     
  4. skratch

    skratch 1/2 ton status

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    I believe that is a test lead for the fuel pump.

    But I'm not positive.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    There SHOULD be no cranking rquired before fuel reaches the Throttle Body. The pump should prime the system in about two sseconds, which is why the pump runs when the key is turned to run.

    That fuel you saw very well could have been left over in the lines from when the pump last worked. It may not have been pressurized, but the fuel lines can easily retain some fuel, as will the filter.

    That lead is I beleive (as mentioned) the test lead for the fuel pump relay. I'm not sure exactly how it is supposed to work.

    I'd almost suspect your fuel pump isn't running, but that doesn't mean run out and replace the fuel pump. It could be the relay, power feed to the relay, perhaps a fuse, etc.
     
  6. Midwestblue

    Midwestblue Registered Member

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    I pulled the line off of the fuel filter and turned the key on and off and sure enough, no fuel. Like you said it must have just had a bit in the line from earlier.
    I know how to check the fuse, but how do I check the relay and to make sure it's getting power?

    Thanks for the info /forums/images/graemlins/woot.gif
     
  7. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    That test lead (spare wire from the fuel pump relay) is there to test the relay. Throw 12v+ at it and you should feel the relay CLICK on and run the pump. I'd check for loose ground wires if the relay is good. Next check power at the pump wires over the tank, and last go diving in the tank to replace the pump! Hope this helps, let me know if you have any questions. I've built a few custom EFI systems for past trucks, I've got some good troubleshooting experience.

    -Dan
     
  8. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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  9. Midwestblue

    Midwestblue Registered Member

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    Thank you! That helped me out big time! I will see if I can get the problem figured out tonight.
     

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