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1997 Chevrolet 1500 Pickup Question: While driving truck died. Pour fuel in manifold & engine will run.

 

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doncam42, 5.7L V8, Terre Haute, IN, October 12, 2013, 16:12
 Rookie

Untill fuel is gone. I have replaced the fuel pump & filter. Also removed fuel lines from top of plastic cover & blew them out with air. Only registering about 25 psi. of fuel pressure. I had fuel tank on bench & applied 12 volts to fuel pump & registerd about 60 psi.Put it all back together & 25 psi. again. HELP............

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  • Answer #1

    ziptie12 October 12, 2013, 16:36
     Master

    Fuel pressure regulator?

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    doncam42, October 12, 2013, 18:13
     Rookie

    removed supply line from top of engine & attached gage to supply line, thinking this would bypass the pressure regulator.Still 25 psi.

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    ProfessorG, October 12, 2013, 20:18
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     Master

    Good pressure on bench at the pump - pressure regulator is mounted on the inside of plenum on injector housing on a 5.7R - removed lines from injector housing - Answer has to be voltage at fuel pump bad or something wrong with fuel line from pump to engine.

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  • Answer #2

    pushrod October 12, 2013, 18:09
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     Master

    Agree with ziptie. Also check for restriction in the line or filter and any leaks! Burnt connector at the fuel pump from high resistance????
    Pump sound like it's turning about the same now that it is back in the truck as it did on the bench with known 12 volts hooked to it, or about the same humming sound when pump is running as key is cycled? It is either a leak, a restriction or low voltage to the pump! IF it worked on the bench it should work in the truck!

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    doncam42, October 12, 2013, 20:21
     Rookie

    Since I changed voltage means from bench to truck, its a very good chance voltage is down going to the pump.I will check it out. THANKS

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    pushrod, October 12, 2013, 20:26
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     Master

    You bet, next time, get a couple of buddies and partially remove the bed, IF it is empty, to replace the pump, leave the tank alone! Hell of a lot easier, especially with those rusty, threaded fittings on this pump module!!! Then testing can be done as well, like running voltage to the puump etc! It would be nice if you could 'carefully' put a full 12 volts to the pump then check pressure. I do, on average, about 3 GM fuel pump replacements a mounth at the shop. On the trucks, pull the 'empty' 'conventional' bed back about 3 feet, no better way to do it! It is about half the work and time that way. That is IF you ever have to do this again.

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    doncam42, October 16, 2013, 15:04
     Rookie

    Problem solved. Low voltage under load, due to poor ground connection from battery to frame of truck.

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    pushrod, October 16, 2013, 15:11
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     Master

    Cool, glad you got it fixed!

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  • Answer #3

    Rojo1 October 13, 2013, 07:03
     Technician

    Try tapping on the fuel pump relay while cranking the engine and watch for pressure fluctuation. Relays are susceptible to oxidation on the relay points and connection to fuse box. If you see anything, try swapping the relay for another in the fuse block of the same type. then check pressure.

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