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.

**Pure Stock** · 09-18-2006, 02:37 AM

Any progress Paul?

**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.

**Killercanary** · 09-19-2006, 10:02 AM

Thanks for all the help thus far guys!

Mike, we're at whits end and would love to take you up on your offer. I don't have your number anymore, can you PM me with it. I think my dad said he had it, if he does I'll try calling you today.

Ed, thanks for the offer! If we can't meet Mike for some reason I may take you up on it.

Mark- that would be a huge help! Is it in electronic format as in something that can be emailed? If so I'd be very appreciative if you could email it to me at killercanary@hotmail.com It seems every diagram I find has 1/2 of the colors and wires that we have, and half are wrong. I've read that there were some changes in '90 in relation to the fuel pump relays and such and maybe I'm missing something to check. I need to call you anyway to catch up, I've been meaning to for like the last 3 weeks, I've just been too damn busy!

Steve-O and Chris- We've checked the grounds that we removed, but I'll check them again just to be sure. Chris, is the thing you are refering to like a older style inline fuse holder in terms of what it looks like? If so its connected.

Joe- as far as I can tell and see, there is nothing there that is left unconnected that isn't supposed to be. I have no updates as I haven't touched the car since I made this original post, and my dad is so fed up with it that he won't touch it unless I'm around. I was in the 'Burgh this past weekend at my in-laws and didn't get to work on the car.

**mlowry1260** · 09-19-2006, 10:17 AM

Paul,

the wiring diagram is a hard copy on 17" x 22" sheets & is several pages. I can get that to Mike on Saturday when I return to the 'Burgh from travel.

Mike's background in electronics would be a big help in troubleshooting.

Mark

**mikeymustang** · 09-19-2006, 10:20 AM

Pm sent

Mike

**Killercanary** · 09-19-2006, 11:07 AM

Thanks Mark. I just spoke with Mike and I think he has everything we need to get this sorted out. If not, I may take you up on your offer. Thanks again!

**mikeymustang** · 09-22-2006, 07:40 AM

Paul:

Call me ASAP! I might be able to save you a trip....there is a "fusable link"( wire wich acts like a fuse) that are sometimes udetectable (by the eye) that they are blow !
This fusable link feeds both the fuel pump AND the CODE PLUG!!!

I pmed you my work number CALL ME!

Mike