Key on- fuel pump won't start, also uable to pull codes

**Killercanary** · 09-14-2006, 10:22 AM

We're having trouble with my dad's '91GT. He was getting ready to have the engine bay painted and I talked him into hidding wires. Well, that has proven to be a bad idea as the car hasn't started for over a month now. When the key is turned forward, the fuel pump doesn't start. I've downloaded every wiring diagram I could get my hands on and we have checked and replaced both fuel pump relays (the on under the driver's seat and the one in the passenger side fenderwell) and the EEC power relay located above the computer. I put a meter on the old and new relays and the results are the same. On the FP relay under the seat, when the key is in the on position I have power to all wires except the green/yellow power wire that according to the diagrams I have goes to the fuel pump. At the FP inertia switch I'm getting a power reading with the key on, but it's only showing about 5 volts. I forgot my paper at my dad's that I listed the colors of the wires on, but the relay in the pass. side fender only had key on power in two fo the 4 wires there.

The other and I fear more serious problem is that we tried to pull the codes with a handheld code reader, when the key is switched on the reader usually beeps and the light flickers on it and then the codes start to come out. Now when the key is on the light goes dim and nothing else happens.

When hooking up all the hot wires we accidently put one to ground. This shouldn't have done anything bad as putting a ground to power would have.

So at this point we're out of ideas. I'm now fearing tha something is shorted in the EEC. I don't know how to test it. I read online that if the injector has power with the key on the EEC is good, but I believe that isn't true since I also read that the EEC activates various things by grounding the circuit. If this is the case then the injector should have power and the EEC would act to ground it to fire the injector.

I appreciate any and all help. I'll post back later with which color of wires had voltage and which did not.

**mikeymustang** · 09-14-2006, 11:47 AM

Worst case I will come out and fix it....let me know what weekend day and I can fix it...I have all the skematics...call me or PM men and let me know

Mike

**mikeymustang** · 09-14-2006, 11:51 AM

or bring it on the trailer on a week day I get home at 3:00 pm...I also have my working A9L

Mike

**Viper_ed** · 09-14-2006, 12:12 PM

I'll give you a call later.

**urgonnaluz2me** · 09-14-2006, 12:58 PM

computer thats what i would say.

**mlowry1260** · 09-14-2006, 01:34 PM

Paul,

Ive got a full size factory wiring diagram for a '90 if you need it.

**Steve-0** · 09-14-2006, 07:20 PM

I would say it sounds alot like a ground is either re-fed back into the power somewhere, or the computer is screwed. Maybe rechecking for voltage in the grounds might help you out...

**Pure Stock** · 09-14-2006, 07:24 PM

There is a connection by the brake master cylinder that needs to be plugged together or the fuel pump will not come on. Are you sure you made this connection when hiding the wires?

**Chris00GT** · 09-15-2006, 01:32 AM

Make sure that the ground wire that used to be at the battery is grounded. The ground wire has a round connector and we get alot of people who do battery relocations forget to reconnect it. If you don't the fuel pump relay won't click along with the ECC relay. After working on my 91 I'm starting to know fox body wiring like the back of my had...hehe.

**Viper_ed** · 09-18-2006, 12:17 PM

Originally Posted by i1arunit

I'll give you a call later.

Sorry I never got around to calling you, been busy as hell lately. I wanted to tell you that I have a Computer I can send out to you if you need it to try and get the car running. I think it was a SD one, but shouldn't matter to get the fuel pump going.