86 GT shut off while driving

[Magnetic82]

Sounds familiar:

While driving the vehicle home recently, I noticed the tach reading erratic. Up and down as much as 1000 RPM over what the engine was actually doing. Car runs smooth. Halfway home a few days later and the car shut off on me. Towed home and today checked it out following the shop manual for TFI-IV ignition testing. Thought the starter relay might have gone south as that happened before but the car would eventually restart but then die. Shop manual says that the stator is bad as is the culprit. If anyone has the shop manual for engine and emission testing, I began at page 15-54 and followed it to the letter. Not bad.
We know that the TFI modules are suspect and I have replaced them in times past for same scenario. I have spare Ford modules and the one on the car now is Ford. The car has not overheated so perhaps the module is still fine. I can easily check it.
The erratic tach and then the shut off seem to point to the stator, which requires removal of the distributor. I can do that and have a shop replace the stator as I have a Ford stator brand new.
Any ideas or thoughts? I'll check the TFI but according to the shop manual, it checks out fine. Fuel pressure is good as that has been a problem in times past as well. Pump does sound weak but 39 PSI when ignition is turned to run and the pump primes. Most fuel components are new as of last March, except the pump. Rockauto sent me the wrong one. Fuel filter is replaced every six months.
Thanks for the help on these mysteries.

[boboli]

Have you checked codes? I think a code 18 would indicate pip failure.
Does the car now run with the new tfi? How about the ignition switch? it's also a known POS

[qikgts]

I think you're on the right track. Stator / PIP (Profile Ignition Pickup) gone bad will exhibit symptoms just as you've described.

Good call on the ignition switch ^^^...

[Magnetic82]

Just finished the repair. The TFI was bad. I checked an older one I had removed about three years ago as well as the one just taken off the car. Both have two resistance readings (according to the manual) that were just slightly out of range. When the new one was installed the car fired right up. Checked timing and test drove it. Wonderful. I was hoping it wasn't the stator. The ignition switch would be another culprit but was ruled out by the step by step shop manual tests.
Seems fuel pumps and TFI modules are the major problems with these cars. I always felt the TFI module goes bad due to excessive engine heat rather than a bad product. The new one is a Ford unit so I'll be watching it like a hawk. My car tends to run warm but doesn't overheat.
Not sure why fuel pumps fail. Glad it wasn't that either. TFIs are easy to swap.
Thanks again.

[Magnetic82]

Just finished the repair. The TFI was bad. I checked an older one I had removed about three years ago as well as the one just taken off the car. Both have two resistance readings (according to the manual) that were just slightly out of range. When the new one was installed the car fired right up. Checked timing and test drove it. Wonderful. I was hoping it wasn't the stator. The ignition switch would be another culprit but was ruled out by the step by step shop manual tests.
Seems fuel pumps and TFI modules are the major problems with these cars. I always felt the TFI module goes bad due to excessive engine heat rather than a bad product. The new one is a Ford unit so I'll be watching it like a hawk. My car tends to run warm but doesn't overheat.
Not sure why fuel pumps fail. Glad it wasn't that either. TFIs are easy to swap. I'll check codes later on.
Thanks again.

[qikgts]

If you have the same issue pop up again check the link below and the prior pages in it's article. It's very easy to understand for all skill level "mechanics".

http://easyautodiagnostics.com/ford/...module-tests-5

FWIW sometimes PIP issues are heat related and they seem intermittent. Not that it's the exact same thing, but when the "pickup" went out in my '85 carbed car I remember the factory manual stating in the troubleshooting section that the "pickup" needed to be heated to a specific temp and tested. Did the manual you were using state the same or similar?

[Magnetic82]

The factory engine/ emissions manual kept pointing to the distributor stator as being bad. But when I pulled codes yesterday after a longer test drive, I received an 11 first, then in CM codes came the code 18. SPOUT inop or something like that. All good now. I don't know how much Ford knew at the time about the module failing but as the manual was printed in 1985 perhaps later corrections mentioned it. But a good mechanic would know. I had a previous 86 GT and the original module was on the car for over 100,000 miles with no problems. I did have an intermittent PIP issue previously but found it best to just replace the module. Unfortunately, I used a parts store module as the car overheated in their parking lot. Convenient. Got me home, then solved the overheat issue- water pump failed. I need to look up TSBs for the module.

[erratic50]

I had the ignition stator fail on my 86 right at 100K and very shortly after it had gotten near overheating. I switched to a 3 core radiator at the advice of the mechanic that found the problem and my car has went 340K+ since without another stator failure.

I long since added a code scanner to my tool Arsenal. Engine computers, one of the best inventions ever!

I went through my share of fuel pumps before I learned a few valuable lessons
1 - fuel is the only thing that cools the pump so when you hit 1/4 tank fill it
2 - in the summer avoid ethanol blended fuels as they don't do as well cooling the pump
3 - DO NOT run excessively large fuel pumps. They recirculate the fuel too much which builds heat
4 - insulate the fuel lines - especially by the right rear tail pipe. Heat transferred to fuel from the exhaust and the hot road causes heat and vapor buildup in the tank otherwise that cooks the pump and can lead to actual vapor locking
5 - Change your fuel filter annually
6 - Run premium fuels when it's hot as they heat up much more slowly