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Hope someone has an

Discussion in 'Chevy Trucks' started by gd8boltman, Mar 19, 2008.

  1. gd8boltman

    gd8boltman Senior Member
    Messages: 326

    answer for this one... Just installed reman engine in 95 gmc 2500. 5.7L TBI, when I installed engine, I replaced the fuel pump, sending unit etc. The fuel pump will not turn off when the key is off. I replaced the fuel pump relay, to no avail. The only way for me to get the pump to shut off is to pull the 20A fuse in the relay center under the hood, any ideas?

    Thanks
     
  2. Sydenstricker Landscaping

    Sydenstricker Landscaping PlowSite Veteran
    Messages: 3,882

    Sounds like a short in one of the wires or the actual relay/solenoid for the pump is staying open, drawing power from the battery
     
  3. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    When you pulled the FP relay did it still continue to run the pump?
     
  4. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    Sounds like it may be a problem in the oil pressure safety circuit... being that you changed the engine I would imagine it is possible that you damaged the sensor or wiring... or maybe even pinched the wire between the tranny and block? This should be the sensor down by the oil filter.

    In the case of my truck, the pump will run even when the key is turned off until the oil pressure drops to nil. The sensor flows power to ground when pressure is there, not otherwise. If that wire is grounded it could keep the pump running indefinately.
     
  5. gd8boltman

    gd8boltman Senior Member
    Messages: 326

    Yes when I pulled the relay the

    pump still ran. It stopped only when I pullled the 20 AMP Fuel Solenoid fuse.
    I installed a new oil pressure sending unit when I changed the engine, and there are no wires stuck between the tranny and the block.
    Thanks for the help.
     
  6. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Disconnect the wiring plug on the OP sender and see if it continues to run.

    You want the one up near the distributor. It's the one that controls the FP. Sender down near the oil filter is only for the gage/idiot light.
     
  7. gd8boltman

    gd8boltman Senior Member
    Messages: 326

    Thanks, I'll give it a shot and let you know, also

    are you aware of the blleding procedures for the Kelsey-Hayes ABS system? I replaced wheel cyls. and rear brake lines, and although I seem to have good pressure at all corners when I bled the brakes, the pedal goes to the floor with little resistance. I replaced the master cyl. bench bled it, rebled all the brakes and still have same issue. I am stuck, and assume perhaps the ABS unit is giving me some grief, rear brakes are adjusted properly.

    Thanks
     
  8. kashman

    kashman PlowSite.com Addict
    Messages: 1,070

    did you bleed them in the right order
     
  9. gd8boltman

    gd8boltman Senior Member
    Messages: 326

    Yes, I started at the RR, LR,

    RF,LF, and pressure coming out of bleeders was good.

    Thanks
     
  10. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    Ooops is it the other way around on his truck? I *think* mine is as I described but its an older model ('87 wiring harness)... sorry if I had it backwards.

    Even a brand new sender could be jammed up inside. Often aftermarket pieces aren't as good as their OEM counterparts...
     
  11. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Can't say I've ever seen a TBI truck that the FP sender was down by the oil filter Derek, but anything is possible.


    100% agree there.
     
  12. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    Well, you know, I thought I was wrong once, but I was right... :D Maybe I'm just thinking backwards but I still suspect that circuit, wherever the heck it is!!! :p