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Fuel pump went out today but?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by toynova, May 2, 2003.

  1. toynova

    toynova Guest

    Went to leave work in my 88 Sub. Started up, ran for about 2 mins then died. No fuel is spraying through the injectors and I can't hear the pump running. I'm sure that I need a new pump but why did the gas guage go from 1/4 to above full and stay there? Got it towed home will dig into it tomarrow.
     
  2. azblazor

    azblazor 1/2 ton status Premium Member

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    You might have some shorted wires, check your pump fuse and relay.
     
  3. HarryH3

    HarryH3 1 ton status Author

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    [ QUOTE ]
    why did the gas guage go from 1/4 to above full and stay there?

    [/ QUOTE ]
    This is usually a symptom of losing ground to the fuel tank sender. Perhaps the ground wire just corroded away and caused the sender and the pump to stop working. Sure would be an easy fix if that's the case! /forums/images/graemlins/cool.gif
     
  4. toynova

    toynova Guest

    I did check all the fuses. OK. Havn't checked the relays yet. Are they the ones on the firewall above the dist.? I was going to check the wiring to before I pull the tank. Would be sweet if thats all it is. The Sub has a 140,000 on it so I figured that the pump would be going sooner or later. The gas guage is what made me second guess the pump. Thanks for the help.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    With no oil pressure (vehicle stalled) you won't hear the pump run anyways, as thats how its set up. 2 seconds of prime when the key is turned to the "run" position, then nothing until there is oil pressure.
     
  6. sled_dog

    sled_dog 1 ton status

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    not srue i understand the no oil pressure thing but I have never heard a TBI Chevy make noise from the fuel pump. I know Vortec Chevy's make LOTS of noise. If you just sit there you can stand in front of the truck and hear it.
     
  7. toynova

    toynova Guest

    Re: Fuel pump went out today but? Update Got it fixed!

    It was the groud wire. The end connector rusted right off. Put a new one on and good to go. Oh ya, it look like someone all ready had the tank out once before. So hopefully it has a newer pump in it. COOL!
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Injected GM vehicles prime the fuel system before a start, as do most other vehicles I've driven that are injected. Thats why I always wait a couple of seconds before turning it to *start*.

    Since the fuel pump isn't run off of the cam, how else would it know when to pump fuel? If it was hooked up to a hot in "run" wire, the pump would always be working, even while you just let it sit there in run with the engine off, which isn't necessary.

    2 seconds to prime the system, but if the "priming system" fails, you WILL have hard cold starts on an injected vehicle, as oil pressure has to reach 5psi (from the GM manuals I've looked at) before the fuel pump is "forced" to start operating again. Which means the engine would have to turn until the oil pump gets the engine up to 5psi oil pressure. This is why there is an oil pressure *switch* in injection systems, not only a gauge *sender*.
     

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