New fuel pump, still won’t prime

[Jesseb302]

Alright, I know there’s a lot of old posts about fuel pump issues. I have a 1991 Ford Explorer . I have replaced the fuel pump. As well as removed the relay and got it tested. It tested good. My wires going to the battery are about as big of a mess as you can imagine so I can definitely have a wire simply not connected to the battery but I am having no luck tracking down a diagram showing what wires actually feed power to the fuel pump and system. My inertia switch at the feet of the passenger floorboard is also fine. This truck is far from a daily driver and it’s easy to access any wires I need to get to if someone can just get me a diagram or even a picture showing clearly what all wires connect to the battery. Thanks for your time

 

[J_C]

The first thing to check is whether there is 12V (relative to chassis ground) at the inertia switch for that brief moment it's supposed to energize the pump when you turn the key to the run position just before attempting to start it. Well, it's also good to check the fuel pump fuse, might be easier to check first.

If there is 12V at the switch, from there it's probably a straight shot back to the pump, so next I'd measure for 12V at the pump, is probably the same wire color as it was coming off the inertia switch.

If you don't have 12V at the inertia switch, either before or after it, then back track to the relay, where there should be 12V on the input contact at all times, not just with the key turned to the run position. Or you could skip back one more node in the circuit to measure whether there is 12V at the fuse, which there should be at all times, not just with key in run position.

Doing a forum search I found the wiring diagram and other misc. bits of related info in the same topic:

Fuel pump wiring

Anyone know how the fuel pump is wired?? Without getting into to much details on what im doing,im just looking for a schematic.. im basically trying to wire a relay to power my BIG pump and need to find a signal wire to turn the relay on.. Ive tested the relay under the hood and doesnt seem to...

www.explorerforum.com

 

[Nadams01]

The first thing to check is whether there is 12V (relative to chassis ground) at the inertia switch for that brief moment it's supposed to energize the pump when you turn the key to the run position just before attempting to start it. Well, it's also good to check the fuel pump fuse, might be easier to check first.

If there is 12V at the switch, from there it's probably a straight shot back to the pump, so next I'd measure for 12V at the pump, is probably the same wire color as it was coming off the inertia switch.

If you don't have 12V at the inertia switch, either before or after it, then back track to the relay, where there should be 12V on the input contact at all times, not just with the key turned to the run position. Or you could skip back one more node in the circuit to measure whether there is 12V at the fuse, which there should be at all times, not just with key in run position.

Doing a forum search I found the wiring diagram and other misc. bits of related info in the same topic:

Fuel pump wiring

Anyone know how the fuel pump is wired?? Without getting into to much details on what im doing,im just looking for a schematic.. im basically trying to wire a relay to power my BIG pump and need to find a signal wire to turn the relay on.. Ive tested the relay under the hood and doesnt seem to...

www.explorerforum.com

Always check the inertia switch!

 

[1sicbronconut]

I've actually seen people install their own fuel pumps and wire them backwards.

 

[dcgerard]

I thought my fuel pump quit and replaced it only to have the same issue. I checked all my fuses and notices my ecc fuse was blown and that keeps the fuel pump from working as well. I tried to replace it only for the new fuse to blow too. I went and got a handful of fuses from the wrecking yard for a $1 and unplugged a few things under the hood until I figured out what item was blowing my fuse. Turns out my coil pack was bad and blowing the ecc fuse, so I replaced it (along with the fuse) and my fuel pump started working again.