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88 chevy runs bad

Discussion in 'Truck & Equipment Repair' started by ken@abf, Dec 19, 2010.

  1. ken@abf

    ken@abf Junior Member
    from NE Ohio
    Messages: 1

    I just aquired an 88 chevy work truck 4X4 with 5.7 throttle body FI. I couldn't get any power to either the fuel pump relay or fuel pump fuse, so I made them hot with jumpers. I got power to fuel pump connection close to tank, but still no pump activity. I opted for a universal electric fuel pump installed in the fuel line. It works but truck idles ruff, then smooths out, then ruff, not much power, maybe I expect too much. It wouldn't suck fuel from tank, maybe cause I used air pressure into the line going to in tank fuel pump and pluged it up, not sure, but I inserted a 5/16 fuel line into filler tube and into tank and to new fuel pump. My question is: can I use the return line that is in the tank for fuel source and block off the return line from the throttle body? With the hose in the filler tube I must have pushed the gauge float, because it shows full and I know it's not. Anyone had a similar problem or know about blocking off the return line from engine.
  2. Dr Who

    Dr Who Senior Member
    Messages: 637

    I would say tht the pump that you put in don't have enuff pressure for the motor to run right., did you leave the old pump in the tank? are you trying to pull fuel through the old pump?

    I think that you may be better off trying to fix the orginal set up, try to find out why the relay was dead, sure it was a ground issue..

    If you block off the return line, the motor will flood it self to death, the motor has to have somewere for the extra fuel it dont eat to go....
    If you unhooked the orginal fuel pump, that is why its stuck on full, the guage works through the pump if I remember right, if not well its probily un hooked.
  3. bill7101

    bill7101 Member
    Messages: 34

    sounds like a bad ground at the stock fuel pump if it constantly read full all the time, its usually a tell tale sign and a very common issue in these trucks