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no power to fuel pump

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by fright89, Mar 1, 2003.

  1. fright89

    fright89 1/2 ton status

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    Location:
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    89 with tbi

    This little problem seemed to come on slowly. First it would not start if I had just shut it off. I would have to let it sit for a few minutes and it would start ok. My fuel pump is a Mallory 4060fi and I can here it when it runs, it is very loud. When it works right it runs for about 10 seconds when you shut off the truck. I think this sucks all the fuel back or something, not sure. This stopped and I think it would flood out a little when I shut it off so it would not start back up if I tried it right away. Then it just died while idling in my driveway, but started fine in a few minuets. Now it just won’t start

    The pump is ok I ran 12v over to it and it came to life with its normal happy whirling sound.

    I have replaced my fuel pump relay and redone some grounds.

    Are there any other modules or relays or stupid stuff like that I could try before I start chancing my wiring harness?
     
  2. fright89

    fright89 1/2 ton status

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    Wiring diag says white/tan to fuel pump. I have two in my harness one is much bigger than the other. Any help. I should remember, I put the pump on
     
  3. HarryH3

    HarryH3 1 ton status Author

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    You need to backtrack in the circuit and see if the fuel pump relay is getting power. It needs a continuous hot on the other side of the contacts and a switched hot to energize the coil. The continuous hot is supplied by the ECM for 2 seconds when the key is switched on, at any time during cranking, and by an oil pressure switch once the oil pressure comes up to about 4 PSI. If you don't have power at either of those spots on the relay, then power will never make it to the pump.
     

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