1986 F150 Stalls when hot

[idaho]

I have an '86 F150 4x4 v8, auto. 3 new fuel pumps and two new modules in the past 6 months have NOT solved my issue!

Truck runs fine when cold. Heats up, stalls for 10 - 20 minutes. Runs fine until hot again. Shuts down for 10 - 20 minutes again. Cools off...runs fine.

I am out of ideas! I have heard maybe a fuel pump relay or ECC with corrision on contacts. Will look at those this weekend.

Two seperate mechanics (both trustworthy) have not been able to solve.

Appreciate any advice.

lotsadogs1@msn.com

[phantom_smack]

Does it lose spark , fuel or both ? The ignition stator in the distributor is a common temperature related problem if it loses spark.

[BroncoJoe19]

As Phantom_smack stated, especially in the early duraspark systems, the pick up coil inside the distributor was known for loosing spark when it got hot.
My friend SeaBronc would ask, does it act like someone reached over your shoulder and turned off the key? If so that is a classic sign fo rthe early duraspark ignition pick up coil failure.

You may also want to pull diagnostic codes.
Here is a tutorial if you don't know how
Code Reader..... - Ford Bronco Zone Forums

[idaho]

It is a duraspark system. Stator replaced 2 years ago (I think). Yes. Someone just reached over and turned off the key.....dead done nada. Cools down, runs like a champ again.

Can I replace the entire upper end of the distributor? Wires, cap, stator, down to the top of distributor? Would this keep it from happening again? I guess my question is should I just replace the entire system with an aftermarket? Thoughts??

Appreciate your input. I am going to work on this over the 3 day weekend. I have not paid attention to the fuel pump (frame mounted) and weather I can hear it or not. Will check that out also. Keep you posted.

matt

[BroncoJoe19]

If its the pickup coil, that's the part that needs to be changed. One can do preventive maintenance on the other parts, but that would not give additional insurance that the stator won't fail again.
IF those parts are bad, changing them is always a good idea.

[idaho]

Is the coil then frying the stator? I am not against replacement of the coil and all associated parts. It's hunting season and this is not good!

[BroncoJoe19]

Idaho, I'm talking about the coil that is outside the distributor, but rather the pick-up coil that is inside the distributor, it may be a different name for the stator.
good luck hunting!

[theoldwizard]

Originally Posted by idaho

It is a duraspark system.

Are you sure it's not a TFI (module mounted directly to the side of the distributor). There were issues with these with the grommet that feed through the bottom of the distributor to the ingition pickup.

Can I replace the entire upper end of the distributor? Wires, cap, stator, down to the top of distributor? Would this keep it from happening again?

Nope. If you do replace the cap/rotor/wires put a little silicon dielectric grease on the contacts inside and outside of the cap as well as on the rotor tip.

I have not paid attention to the fuel pump (frame mounted) and whether I can hear it or not.

I'm pretty certain the pump is in the tank. What you think is the pump is actually the fuel filter. When was the last time you changed that !

[BroncoJoe19]

Originally Posted by theoldwizard

I'm pretty certain the pump is in the tank. What you think is the pump is actually the fuel filter. When was the last time you changed that !

I have a '90 full size bronco. The F150's twin sister

Prior to 1990 they had TWO fuel pumps, a low pressure high volume one IN the tank, and a low volume High pressure one under the truck on the driver's side frame rail. It was in 1990 that they went to a single in the tank high pressure unit.

I believe that the fuel filter is under the truck for both systems.

Haynes has about four pages dedicated to trouble shooting the fuel system, and a good amount of it is dedicated to differenciating issues in the two pump system.

BTW. I have seen a bad coil (the big one that is outside the distributor) fail after it gets hot, but my much stronger suspicion would be go with the one that it inside the cap.

OK... one last thing.... I just went to AutoZone.com - Get in the Zone! and entered in 1987 ford bronco 5.0 engine as one of my vehicles. I searched for pickup coil and got this...
http://www.autozone.com/images/produ...wl2f122003.jpg

I searched for ignition control module and got this...
http://www.autozone.com/images/produ...wl2f121003.jpg

Looking at that ignition control module, I "think" you have a duraspark II ignition system, NOT an early duraspark. SO the problem could also be the ignition control module. WIth hunting season around the corner, I would either pull that and have it checked or swap it out. It's about $40.

Good luck man... and happy hunting!

[broncofun]

i had a car that did that in summer time,it ended up being that the fuel lines were too close to hot engine compartments,the heat from lets say the manifold would vaporize the fuel before it reached the carburator,i re-routed the fuel lines and insulated some.it fixed the problem.