Wiring diagram

[BobbyE]

Trying to find a wiring diagram for GT-RA #41
Josh at Panoz is looking, but not sure if he can find anything
as the school cars seem to have been modified without documentation.
Our problem is, when you turn the power on and flick the ignition switch
the fuel pump does not cycle, (the fuel pump is working)
There is spark, power to the injectors, but the car won't start, plugs
come out bone dry.
Wired the pump to run all the time, still the same.
Hooked a code reader up to the self test port, nothing, no codes, no
power.
We are getting power to the EEC relay and FP relay, as we understand
the computer does grounding to activate the injectors...
We have checked and made sure all grounds and connectors are clean
and secure, the car ran last year when we put it away, we did nothing
that should have caused this.
We think the computer may be dead, without a wiring diagram this is
hard to check and verify.
VERY FRUSTRATING.

Any ideas or wiring schematic would be greatly appreciated.

Thanks,

Bob

[Gatorac]

The engine and computer harness are basically the same as a 87-93 5.0 Mustang. Hayes manuals for those year Mustangs will have wiring diagrams in them. They are tiny and hard to read though. Several years ago I picked up some large wiring diagrams. They are from Ford and the part number is FPS-12136-93E. I don't remember where I got them from. There is a phone number in them- Helm Inc. 1-800-782-4356

[Gatorac]

Another thought is try and get a hold of the Ford Motorsport SVO Multiport EFI Engine Management Harness Installation Manual. This is the harness we have in our cars. The instruction manual sheds a lot of light on where the computer/engine harness integrate with the cars wiring harness. The publication number is ISM-12071-C302. It used to be available from Ford Motorsport for $5.00. You had to mail them a check and wait for it. Here's a link to one posted on the internet. http://www.vintagebronco.com/newberr...h/efi/efi.html

[jmimac351]

Bob, I may have misunderstood you but have you replaced the fuel pump relay? A basic 30amp relay will plug right in. I've had one go bad before on my '92 mustang.

[eric1h]

Did you make sure the key is still wired under the dash? The key needs to be on for the security chip and ECU to function

[jmimac351]

Key? Que?

[Gatorac]

Key may be needed for the 4.6 but not the 5.0. 5.0 is old skool.

[Blue Streak 21]

I had this same problem with my car last year. Have you checked the fuseable links in the harness? I had one go bad in my system while I was chasing my electrical gremlins. To diagnose the problem I pulled the harness out of the car, unwrapped it up and found a couple of bad wires and a possible short down one of the O2 sensor wire branches.
The harness also had a bare wire near the big ECU connector. The wire was rubbed bare where the harness crosses the raised edge of the metal shelf that holds the ECU.

[BobbyE]

Thanks for all the info. I managed to look back into the forum pages and found some good sites that Jim had posted.

We were getting a very weak signal at the ground port on the EEC relay,
this suggested a bad ground!! and it was getting a wee bit of power from
a sensor.
We started disconnecting stuff to see if the light would go out. We were
probing at the mass air connector and hooked the test light to ground where
the bolt on the frame rail, that holds on the frame rail brace, we were not getting positive power, put the test light to battery positive, no light.

That point where we were grounding also had a ground strap under it !

Cleaned it up, and guess what... it all works again

We thought we had done everything, but I guess not.

Now to get it ready for our track day at Mosport.

Thanks again,

Bob

[eric1h]

Yeah, on the 4.6 at least under the steering wheel there is a key electrical taped to the ignition box that was strapped to the side of the steering column

[Panoz Paul]

Greetings from Minnesota ... BIR is open for the season !!! First day , I had a goblin show up ... thought was the fuel cell , checked out ... The car looses all power in right hand turns only ; not good at full throttle / 5th gear in corner two ; then prgressed into lower speed right corners ... Its almost like a kill switch is hit ??? .9 mile straight into a 10 degree banked corn one is fine ... I've printed the wire diagrams from the earlier tread to start the hunt ... Looking foer any clues ... Thanks / Paul W.

[eric1h]

Originally Posted by Panoz Paul

Greetings from Minnesota ... BIR is open for the season !!! First day , I had a goblin show up ... thought was the fuel cell , checked out ... The car looses all power in right hand turns only ; not good at full throttle / 5th gear in corner two ; then prgressed into lower speed right corners ... Its almost like a kill switch is hit ??? .9 mile straight into a 10 degree banked corn one is fine ... I've printed the wire diagrams from the earlier tread to start the hunt ... Looking foer any clues ... Thanks / Paul W.

Classic fuel starvation. Open the fuel cell and check for a blockage In the fuel pickup box

[Gatorac]

This should be easy to confirm with a fuel pressure guage.