From: skod@indianajoe.Eng.Sun.COM (Scott Griffith, Sun Lumpyware)
Newsgroups: rec.autos.sport
Subject: Re: HELP: Mustang GT wont start
Date: 28 Dec 1992 21:53:32 GMT
Organization: Sun Microsystems, Mountain View, CA
NNTP-Posting-Host: indianajoe
Summary: Mustang tech- please hit "n" if not interested. I won't do

In article <BzzLFq.Jyo@news.cso.uiuc.edu> djr48312@uxa.cso.uiuc.edu (Dennis Robinson) writes:

>I've recently bought a used 1989 Mustang GT with 46k miles on it.  Today was
>the first day I've had any trouble with it.  I was driving along in 1st gear
>, at the same time reaching under the driver seat for something.  I ended up 
>
>and eventually the engine started running.  There was plenty of electrical juice
>and eventually the engine shut off.  There was plenty of electrical juice as
>when I turned the key the starter had its usual vigor.  The radio and lights
>were fine.  I saw that the "cap" I had in my hand fit on some kind of thing
>under the seat.  There were three wires going into something what I know
>nothing of, there were rows of metal plates and a spring in some 1" x 1"
>device of some sort.  There was black stain on the metal as if it had been
>shorted or something.  I tried to start the car about 5 times, the starter
>was fine.  So the problem is fuel, or ignition.  Thats all I have now, Im
>about to take a spark plug out and set it a half inch from the block and crank
>to see if theres spark.  Any clues about this "device" or anything else please
>reply..   

What you grabbed under the seat there was the fuel pump control relay.
The fuel pump is run by the EEC-IV engine controller, and that relay
is used to switch the power on and off to the pump. If the pump's not
running, you have no pressure in the fuel rails to the injectors- so
it sure enough won't start! When you first turn the ignition on
(before you begin cranking), you should hear the fuel pump pre-run for
1-2 seconds to pressurize the rails, then shut off (it is located in
the tank, and will sound like a quiet high-pitched whine under the
carpet at the very rear of the car). Once the car is started, it runs
continuously. If you don't hear the pre-run when you switch on, the
fuel pump's not working.

When you pulled off the "cap", which is actually the dust cover for
the relay, you probably allowed some portion of the relay to short to
the bracket that holds it to the belly pan. This either a) fried the
socket that the relay fits in, b) broke the field winding on the relay
coil somehow, or most likely c) fried the fusible link that supplies
the power to the relay. It uses a fusible link up by the starter relay
(left front of the engine compartment, between the strut tower and the
battery, under a plastic cover), not a fuse, BTW. I'd check that
first, then pull the relay out of its socket and clean it. While it's
out, check the coil resistance for an open, and the contact resistance
with the relay armature pulled in. Then put it back in, and things
should work fine. 

If the fusible link is good, the relay is good, and the socket is
good, then what you have done is to blow up the FP control output on
your EEC-IV box, which means you get to buy a new one. Nothing good
has _ever_ been said about blowing up the EEC-IV box.

Tape the dust cover _securely_ back in place before you reinstall the
relay under the seat, BTW. A ty-rap, strategically placed, would not
be excessive to prevent future reoccurences.

Oh- and you'll generally get better responses to this kind of question
over in rec.autos.tech, or better yet on the Mustangs mailing list
(mustangs-request@hpda.cup.hp.com). Normally, this kind of thing
receives a fairly acid response here in rec.autos.sport (which is
normally intended for discussions of motorsports), but the traffic is
low due to the holidays. And I can't resist helping out a fellow
Mustanger. And no one will flame you three days after Christmas,
right?  Hope that this helps- best of luck, and happy (ier!) holidays!

-skod

--
Scott Griffith, Sun Microsystems Lumpyware
expatriate SCCA New England Region Flagging/Communications worker
(and sometimes driver, of anything that turns both right and left,
and can pass tech...) Return Path : skod@trenco.Eng.Sun.COM
Newsgroups: rec.autos.sport