I doubt anybody will know the answer to this but I figured it's worth a shot. My 98 z28 has a problem with the fuel pump. About 1 out of 10 times (only after sitting for a few hours without being started) it will not engage, so I cannot start the car. After hours of messing around with the fuel pump wires, I found out that for some reason the fuel pump ground wire was spliced into the power seat ground wire (last owner did that I guess). The ground wire is then bolted right under the dash next to the hood pop handle.

I can get the fuel pump to engage if I disconnect the ground wire from the bolt - then lightly touch the ground wire to the bolt - then hit the button on the power seats to move the seat - which makes the ground wire spark since the ground is only lightly touching the bolt. After a few sparks fly, I can start the car right up, and drive for hours. It's like I'm using a defibrillator (thing that is used to shock people back to life after their heart stops) on the fuel pump.

I thought maybe there was just a problem with the spliced power seat wire, so I removed the splicing and bolted the fuel pump ground wire separately to the body of the car (no other ground wires attached to it). It started right up a few times within 2 days but then it did the same thing; the fuel pump wouldn't engage. I was in a parking lot and ended up having to splice the fuel pump ground wire back into the power seat ground wire so I could make it spark. Once it sparked, it started right up and I drove home.

Does anybody have any idea what would be causing this? Thanks.

 

sounds like a bad fuel pump.

 

Could be a sticking fuel pump relay. The fuel pump itself is grounded on the left rocker panel. There is also a connector outside left of floor pan front of rear axle. The relay coil gets 12 Volt from the PCM, and the relay contacts get 12 Volts from the Fuel Pump Fuse. The relay contacts pass the 12 Volt power to the pump.