Fuel Pump Issues

Don Fiveolio · Jun 26, 2005

Alright so here's the deal,

When I first got my 90 GT about two months ago, the first thing I did before I put it on the road was upgrade the alternator to PA Performance 95 amp (the first one would not stop smoking), but I have never stopped having electrical issues. On two seperate occasions, I turned to the key to get ready to start the car, but when I hit the ignition, all of the power would go out. It turns out that the terminals were dirty as hell so I scrubbed them with a britsle brush and got brand new battery cables. Before I started the car, I changed the location of the ground from its normal spot to a fender mount. I started the car later that evening to go out for a drive and my gauge showed a charge that was better than ever before, but when I got home I noticed the fuel pump would not stop running.

I pulled code 95 from my reader and all of the other threads that I have been reading show that their pump has issues perfoming, but mine won't stop performing!!!!!!!!!!!

Should I just check all of the same areas that the other threads suggest to check or is there something else that I need to look for?

Vipersix · Jun 26, 2005

The code literally is: Fuel Pump Monitor (FPM) signal - indicates circuit problem.

So... when people relocate their ground I like to recommend that you run an additional line from that point back to the original ground on the block. Ground issues can wreak all kinds of havoc if you're not careful. If you have a powerful aftermarket pump I'd even run its own ground line to the battery or the nearest negative terminal from the battery.

Otherwise... yeah, follow what the other thread recommends.

HISSIN50 · Jun 26, 2005

A latched EEC relay can keep the FP relay energized, as can a latched FP relay.

I would probe the FP relay socket when it does this (pump runs when it should not) and note what values you have (to see if the FP relay latched or if the EEC relay is still on).

You can pull the FP relay to shut it down.
And yeah, code 95 generally means that the FP lost power at some point when it should not have. This can happen for 1/10th of a second or longer.

Good luck.

Don Fiveolio · Jun 26, 2005

Thanks a mill. I'll make sure to check for that. The pump runs untill I pop the hood and disconnect the negative cable (I'm doing this while I have my keys in hand).

Are relays easy to fix or replace?

Thanks again

HISSIN50 · Jun 26, 2005

THe FP relay is under the driver seat on your 90. Takes 30 seconds to replace. EEC relay is more of a pain to access (above the puter).

Good luck.

vikingpower · Jun 26, 2005

Vipersix said:
If you have a powerful aftermarket pump I'd even run its own ground line to the battery or the nearest negative terminal from the battery.

What is a good starting point for pump capacity to do that, I have a 255 and it burned out the fuel pump fuse link at the battery and melted the rest of the wire's insulation into the carpet near the relay under the drivers seat. I checked some of the rest of the wiring from the relay to the pump and it seemed ok, but I didnt check the ground becuase I have to pull out the tank again, ugghhh.

Fuel Pump Issues

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