Super Coupe dies after warmed up

DABROUDS

MEMBER
1991 FORD THUNDERBIRD
150,000 MILES

25 year ASE Master
& I am helping a friend over 1000 miles away over the phone. And I am looking for an answer to the question of "has anyone else had this SAME problem"?
he has a 91 super coupe that he has been stabbing in the dark for 2 weeks now, NOW he calls me!
ANYWAY, the symptoms are that if he lets it sit and run it will run fine forever.
when he drives it 10-20 minutes though it will begin to fluctuate on the temp gauge and die. NOT overheating, and he has not replaced the thermostat(one of FORDs recommendations)
when it dies It has spark but no fuel. After it cools down it will start and go about 5-10 miles and repeats the same problem
THINGS HE HAS REPLACED:
fuel pump & filter, cam & crank sensors, ignition module, EEC and Fuel pump relays
I think the list is longer but he didn't go into that further.
I have told him to start with the basic stuff. Spark, fuel, timing
Not sure what is shutting the fuel down but HE went and replaced the pump before diagnosing the problem.
I also told him to jumper the inertia switch and see if that does it (had several of those go bad when I worked at the Ford dealer in the 90's)
So what I am really asking is "has anyone else had this SAME problem"?
maybe there is something common that I am missing?
Crank No Start till it cools down has spark and will start on throttle body cleaner

3 Replies

HMAC300

MECHANIC
48,601 POSTS

First what engine is in this 3.8 or 5.0. Second it seems to be definitely a fuel issue. That being the case do you think that possibly the fusible link that powers the relay may have only one or two strands still connected and when it gets warm/hot it finally loses connection? I have seen fusible links do this. I imagine either the one for the eec relay or the fuel relay would do the same. Also what Is fuel pressure when cold and then when it acts up. Is it a possible oil pressure switch going bad as the fuel system is normally connected to that and the relay normally only does initial pressure activation. Being the car is over 20 years old are the connections any good and not shorting someplace- a very high possibility. I know you are the second party and trying to help out but stuff has to be all found out before you rack your brains out trying to find an answer. Only other thing that I can think of is the grounds for ecm aren't good or the anti theft if equipped is messing with it

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Friday, July 19th, 2013 AT 7:45 AM

DABROUDS

MEMBER
2 POSTS

HMAC300,
thanks for the reply :) you are spot on with all of your suggestions for the 3.8liter Super Chicken. I have ran all of the same things down to my buddy. The one thing I did not consider was the fusible links GOOD ONE! I will run that by him also this morning. The oil pressure switch only feeds the gauge and does not send info to the ECM so it will not be able to shut anything down:( good thought though.
The first thing I did for him is send the fuel system wiring diagram from ALLDATA as well as all of the 15 ground locations and tell him to check every single one! Last I told him that he needs to get a fuel gauge taped up to the windshield or ran into the cabin to see what is happening when the event occurs. I think we are definitely on the same page. What I was really hoping for was someone else that has herd of the same problem and had an answer for what they found. Thank you again for your help. More to come.

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Saturday, July 20th, 2013 AT 4:23 AM

HMAC300

MECHANIC
48,601 POSTS

I can understand that cause it never happens only once. Other than the things I've thought of can't think of anything else though. Oh well hopefully he'll find it.

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Saturday, July 20th, 2013 AT 5:43 AM