Fuel pump won't turn on unless wired to battery

meltmanbob

Member
Dec 18, 2002
392
0
17
san diego CA
Ok I had a HUGE brain fart while working on my car the other day and hooked the battery up backwards. I got distracted by someone talking to me and just wasn't paying attention not to mention I had been up for almost 2 days straight trying to get my car back together after replacing the evaporator and heater core and relocating about half of the wiring in the engine bay.


So here's the problem, my fuel pump is only seeing about 8 volts. If I run a wire directly to the pump's red/black wire and bypass the car wiring it turns on. At first I thought I fried the Ignition Control Module so I replaced that. Tested the alternator and that was bad so I replaced it with another 3G from the JY after Autozone checked it and said it was good. I also replaced the fuel pump relay and checked every fuse and fuseable link I could find. Still 8 volts at the pump which is what I was getting before I replaced anything.

The red/black wire from the fuel pump splits into 2 red/blacks, one to the relay and one to a connector in the driver kick panel but I can't follow it very far after that.

The relay has a red/black, tan/green, orange/something(blue I think), and a yellow I think. The red/black on the relay goes to the pump but I haven't traced it so I'm not sure if it's a direct shot or if it goes into something else along the way. It looks as though the tan/green is the signal wire which I traced into the engine bay to a connector where it turns into a green/red wire which I then lose at some point after it goes back into the car.

The relay looks to be getting power directly from the starter relay hot side.

Does anyone know what signals the fuel pump relay to come on? Is it the ignition or the computer? So far it seems like maybe one of the wires is fried a bit and not passing all the voltage or a fuse link somewhere. Basically any help especially about the wiring and where it goes would be greatly appreciated. I think I could troublshoot this ok if I could see how the circuit is supposed to flow but I don't have my toner any more so it's hard to trace the wires.
 
  • Sponsors (?)


Also my battery gauge won't read accurately anymore. It goes up a few marks on the gauge when I start the car but it used to go up to the halfway point and a little above once I put the 3G alternator on. This still happens even with the new ok alternator yet if I check the battery voltage it's up around 13.8v so it appears the alternator is charging. Any thoughts?

Why is it none of the fuses or fuse links blew with regards to any of these problems?

When I pulled codes I'm getting primary and secondary fuel pump circuits fail but that's because I'm bypassing them I guess, the one code that confuses me is an EGR low voltage code which up until my brain fart I had cleaned everything up and had no codes. So much for getting it smoged.