Hello,
My 86 f150 (302 fi) has started to die on me, it has quit while I am driving or after I get to a destination it won't start, however if I let it sit for a couple of hours it will start up fine. Friend says trash in fuel tank, I don't want to go bankrupt buying parts to chase the problem down. Any suggestions? thanx

 

You need to check for any codes from your EEC first. Start there.

 

Yes, check for codes and also check for spark and fuel. You are correct, it could be a lot of things, but these tests will lead you down the right path from the start.

 

Sounds like an ignition module or coil. Based on your description it appears to happen when the truck is hot. When you shut off the engine you can get soak back and the temperature under the hood will actually increase for a period of time since there is no coolant flowing or air flow. When it happens check for a spark.

Erik
'85 F150
300-6 4sp OD trans

 

I agree with ebodell. All of the ignition problems I've had on various vehicles always rear their ugly head when components heat up. The vehicle will run great until it gets up to temp and a bit hotter under the hood, so I'd check out the ignition system first.

A clogged fuel system will stay clogged.

 

I have a good 1986 F150 XLT reg cab long bed with EFI 302 story. Fairly nice truck, light desert tan, brown interior, AM/FM cassette, cloth bench seat, power door locks and windows. What's not to like?

Same story. It would shut off randomly and then not restart for a while. Sometime it did restart immediatly, but not too often. It started this behavior by shutting the engine off and on rapidly while driving, as if you cycled the ignition key rapidly, and then progressed to staying off over the period of 1 year. Fairly annoying, especially when it did it on the highway in rush hour traffic, which was very often. I took the truck to 5 different dealers around Dallas. Nada, zip, no one knew what was wrong with it. I replaced:

Fuel pump, Duraspark ignition module (3 times), TFI module (2 twice), ignition coil, the entire distributor/cap/rotor assembly then set the timing, spark plugs, sparkplug wires, dropped, drained and cleaned the front fuel tank (rear tank was not usable due to a dead fuel pump), fuel filter, fuel pressure regulator, manifold/atmospheric pressure sensors, ignition key cylinder, the battery and cables, grounding strap, floor mats, windshield, dashboard cover, new sealed beams, drivers side window motor, new AC compressor, hoses and evaporator, new shocks, I put a little pine tree that stinks. To no avail. I spent a lot of money on parts and on clueless dealers. (Close to $3K!!)

One day, my wife and I were cursing at it in a parking lot. We had just gotten the blasted thing to restart and it was idling with the hood open. My wife asked what part we had replaced last and I told her the TFI module and pointed it out. She touched the wiring bundle leading to the TFI and the truck died. My first thought was that the truck didn't like my wife and I was preparing to file for divorce, however, further testing proved that the wiring harness to the TFI module had an internally broken wire (that was not visible). The fault was in the wiring connector that plugs into the TFI module on the side of the distributor assembly. Some trucks had the TFI module on the driver's side fender, but mine had it on the distributor which with years of vibration caused the wires to experience metal fatigue and an intermittent open circuit. I bought a new pigtail (connector assembly with a 6 inch length of wire bundle) and replaced the wiring as far as I could reach. There's like 9 wires if I recall, but that was in 1996, so perhaps drug, sex, and rock 'n roll has fogged my memory.

When I bought the second TFI module at Chief's Auto, there was a guy there with another 86 F150 that had the same problem. His TFI was on the fender well and required a thin-wall socket to remove.


(He had a gray and red truck, so the problem might have been different with his truck, also, he had a yellow colored pine tree that stinks while mine was green.)

Anyway, it may not be the problem you're having, but it is quick and easy to check and eliminate that possibility.

 

Im going nuts please help. My 86 150 runs great when im driving interstate. In traffic "stop and go" it will sputter and punk out so I have to push it off the road. When I try to start it the motor will labor like a battery is going dead. When it "cools down" she starts right up. Than again a few minutes late she does it again. I thought the thermostat was bad so I took it out and she still does it in stop and go traffic.Its been happening so long and stranded me in the worst places. I've cleaned the module on the side of distributor and of course no luck. Im ready to set fire to it. Please help

 

Bill....what engine do you have, and especially if its EFI, have you pulled any codes?

 

I have a 302 efi. I change fuel filter.pump have checked all injectors took out thermostat. Will pull codes. Just though somebody would know

 

For the love of god pull the codes!!!!!!

 

I agree, sounds like a failing ICM, Ignition coils should be changed at the same time, many times they are part of the reason the ICM goes bad

 

Thanks guys Ill try the icm and change coil. Hey why are the 2 girls covering the 3 beautiful kegs of beer.

 

Throwing parts at a problem because some guys on the Internet said it "sounds like it's
this" but who have never even seen the thing much less truly diagnosed it is the
wrong way to go about it.

On any computer-controlled engine, first thing to do is ask the computer what *it* thinks
is going on.

 

While very true and I generally agree on these older rigs with questionable service histories you can't really do any harm by replacing 10-25 year old components with the except for the rock steady ds2 module.

 

I disagree. I don't know how many times I have replaced original perfectly functioning(though very old) factory parts with new replacement aftermarket parts, and had them fail or cause problems right out of the box. That's why you really have to know what your problems are in the beginning, and then find out what the problems are after you work on it. If you find you have more problems than when you started, most likely it's from mistakes you have made on the installation, or defective "new" parts you have installed.