Fuel Pump Problem-- NEED HELP!!!

Discussion in 'Chevy Truck Forum' started by fixeruper, Jul 12, 2012.

  1. fixeruper

    fixeruper New Member

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    I own a 1987 Chevy C10 Pickup with a Holley Throttle Body, 2WD, Fuel injection. The fuel pump stopped working on me and truck died. Replaced pump, and it is still not starting. Checked volts going back to fuel pump and it's showing it's only getting 6 volts, instead of 12 volts. Not sure what the problem is??! Can anyone give me advice or refer me to a wiring diagram so that I can check to see if it is the wiring or a bad relay or what?! Any advice would be greatly appreciated, im desperate!! :confused:
     
  2. chevychase

    chevychase Senior Moderator Staff Member

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    Check connections good are you getting a good ground? Here is a diagram where are you checking power at will be tan and white wire or orange at fuel relay.[​IMG]
     
  3. fixeruper

    fixeruper New Member

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    Grounds are good...found the relay.. what next? How do i determine if its a bad relay or not?
     
  4. chevychase

    chevychase Senior Moderator Staff Member

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    Can put 12 volts to orange wire . or put 12 volts to terminal g here [​IMG]check see if getting power to the fuse 12volts.
    Could be either relay ..bad wire ...corroded or bad fuse..ignition switch...bad ecm ..oil sending unit or real low on oil .
    First thing to check run 12 volts to g terminal see if pump comes on if not a bad wire connection to pump or at pump.
     
  5. chevychase

    chevychase Senior Moderator Staff Member

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    You bypass all when jumping terminal g ..relay ..ecm ..all

    That would be b2 on wiring diagram terminal g
     
  6. fixeruper

    fixeruper New Member

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    Thanks for the tips and diagrams!! gonna have to check those things tomorrow...rain got me shut down! appreciate it man!! Ill get back on here with feedback!! I'm definitely a better carpenter than a mechanic lol
     
  7. 87c10slammer

    87c10slammer Senior Member

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    check your ecu fuse. had the same problem in my 87.
     
  8. chevychase

    chevychase Senior Moderator Staff Member

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    Will be the cigarette lighter fuse.
     
  9. chevychase

    chevychase Senior Moderator Staff Member

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    When you check for power at pump or relay will only have a few seconds . Ecm will send power to relay via the green and white wire at relay.
    Turn key to on do not have to crank on engine. If you get power at green and white check for power at orange wire .
    If you get power at orange wire check for power at fuse . Circuit goes ecm..relay..fuse..then pump.
    When you turn key to on will have few seconds to check..will have to turn off key for 5 seconds try again .there is a small delay.
    Can you hear relay click when key turned on? This truck does not have security does it? Check the black and white wire for good ground off the relay.
    Check the bulk head connector good connection and clean.
     
  10. Boudin

    Boudin Forum Moderator

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    Relays can be tricky to check because they will work a lot of the time when testing them because they are only bad when hot sometimes. Pull the relay. Take the positive and negative wires from a 12 volt source (battery works well) and put it to the two pins that are parallel to each other. You should hear a definite click in your hand as you hold it.
     

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