[83trekker]

So last september my fuel pump went out in the bush, had the truck towed to my house and went to Napa and got a new fuel pump. This weekend back in the bush , the fuel pump stopped working in the afternoon, than around 9 hours later when it got pretty cold out the fuel pump started back up again, same thing that happened when the original one went out. So i was pretty sure the fuel pump was no good and didn't want to trust driving it back on the highway home incase it crapped out again when it got warm again. So having it under warranty i popped it out got a ride and swapped out another new one from napa.

Get back to the bush install the new fuel pump and nothing it wont prime up at all. Swapped out the replay with 3 other ones and checked the fuse which was always good. I then jump the 2 pins where the fuel relay is then the fuel pump primed up and truck started and has run no problem,pulled my jumper out, through in the relay and everything is back to normal. Any ideas why it didn't just start up and prime with relay in it? I unplugged the battery for a while and nothing till I jump those 2 pins. Thanks

 

[freecableguy]

Most vehicles have a sensor that will automatically inhibit power to the fuel pump if a significant enough negative g-force is registered i.e. you got in a collision and avoidance of a continuously fed fuel leak would be advantageous as it could lead to a fire and/or explosion. It's possible that sensor is bad. That's about all I can contribute but might get you working down the right path...

 

[GrouchyOldMan]

The fuel pump has no such circuitry in it. It is wired to blow the fuse if it gets in a accident and shorts the wiring. That's the way GM wires it. Is the pump connector square or oval? Are your grounds tight? Try swapping the relay.