Dath

Just brought my 89 outta storage (6 years) and having a fuel problem. In tank fuel pump won't kick on and pressure the line when you turn the key. Tested the relay under the hood (passenger side) and its got juice on both ends. Tested the relay in the hatch and thats fine (getting and giving juice). So figured the in tank pump was toasted. Dropped the tank, ran wires from the battery directly to the in tank pump to test it and it kicked on. Confusion set in. I then traced the 4 wires (2 black, 1 tan w/ blue tracer, 1 yellow with black tracer) as far as I could...from front relay to comp and then from pump to shut off behind the taillights. Everything looked fine. More confusion. Had a few beers to help me think. Didn't work. So I hot wired a direct line from the hatch relay to the pump...kicked on, runs great. The only negative thing I can think of with this set up is flooding the engine if I pause between turning the car on and turning it over.

Two questions?

1. WTF?
2. Will the direct line burn out the pump even though it still has 2 relays before the hot wire?

The mods on this stang are listed below.

FiveLiterRiceEater

try switching the FP relay with a known good relay. just because it has power on both sides doesnt necessarily mean its good.


also, how was the connection at the rear relay and the fuel pump itself? maybe it was just a bad connection. or you could have an open between the rear relay and the pump.

TENGRAM

FP relay, thats under the driver seat right? the "relay" in the back is the inertia switch. did you hit the button on top?

FiveLiterRiceEater

no idea. FP = fuel pump. what relays did you test? if you checked the wrong ones that might be the whole problem

865.0trunk

ya, the fuel pump relay is located under the drivers seat, it could be that but i doubt it. if the relay has power, try bashing the tank with a rubber mallet, sometimes that will kick the pump on, if it works then you need a fuel pump for sure

Dath

Did that right off the bat with 2 good relays...took them right off the rides of 2 of the guys helping me that have 5.0's. I should have mentioned that. My bad.

Like new.

A bare wire? If so, then no. Not sure I understand you correctly on that though.

I never found that when tracing the lines, but I stopped at the comp. Will check for this first thing in the morning. Thanks man.

Yeah. One of the first things I did was pop the panel off and reset the switch. And I also hit the switch about 47 times thoughout the day as I tested different things.

Strong possibility. The under seat relay may be the issue.

I know its a good pump since I tested it with a direct line to the battery and it now works fine with the hot wire.

Thanks for helping me brainstorm this guys. Greatly appreciated.

FiveLiterRiceEater

i think you probably just tested the wrong one try the one under the drivers seat and let us know how that goes

Dath

I think you're right and will do. I just got off the phone with one of guys helping me and he responded with a solid, Homer Simpson "Doh!" First thing in the morning I'll know.

Dath

It was the relay under the drivers seat. Switched it out and removed the hot wire...ran like a champ. Thanks again fellas!