View Full Version : Ford F-150 won't crank after engine warms

02-26-2005, 08:26 PM
Could use some help! My 1991 F-150 (5.8 fuel injection) won't crank after the engine warms up. I have replaced the plugs, wires, control module on the distributor and MAP sensor. This seems to have helped some, but still have the problem with the truck not cranking after it runs awhile. Any suggestions? Thanks!

02-26-2005, 09:37 PM
Welcome to the forum Mr. Frizz!

I assume when you say "wont crank" you mean the engine will not turn over when the key is in the start position. You say it won't crank when the engine is warm.

Several things come to mind. First would be your timing needs some work. The next time it won’t crank try moving the distributor.

A weak or tired starter will exhibit problems when warm.

Then there is the dreaded "Heat Soak" which for me has never been a problem on any of my Fords.

This is if you have a No Crank situation. If it has a "No Start" condition and you are describing it as a No Crank condition you need to let us know and I'll take you down the long dark path of TFI problems.

Also, Have you pulled the codes?

02-27-2005, 01:26 PM
Thanks for the reply. There isn't any trouble with the starter. The truck will crank when the engine is cold. After it runs for awhile, the truck won't start back up, the engine just turns over. If I let it set for awhile, there is no trouble with cranking, but the engine skips, and I can smell fumes. Several people have suggested that it's the cadilitic (sp?) converter. Also there's not much power when driving.

02-27-2005, 01:56 PM
I highly doubt a plugged up catalitic will cause this problem, or any other problem with a cat. But if you want to trust them you can take out the o2 sensor and that will be an opening in the exhaust system beofre the cat, if the cat is plugged up the exhaust will escape through the hole where the sensor was and should run fin all the time and start everytime.

It could be a bad fuel pressure regulator.

02-27-2005, 02:25 PM
He needs to determine what's NOT happening when hot. Is it lack of fuel or (most likely) lack of spark.

02-27-2005, 09:58 PM
Both of you guys are correct.

First we need to get the codes. Even if the Check Engine Light is not illuminated the computer still stored a code.

Pull your codes or get then pulled and that will point everybody in the correct direction.

02-28-2005, 02:09 AM
Forget the codes...Id like to see data streams. j/k lol

02-28-2005, 08:24 AM
Ford had some problesms with their ignition modules on some of their cars, maybe some of their trucks? Don't know. In any case it could be the ignition module that is creating an open circuit when hot, then when it cools the circiut contracts and makes contact again. Like dougbfresh mentioned earlier; sound like lack of spark.

03-09-2005, 12:50 AM
Where is the ignition module located? Someone else told me that may be the problem. Thanks!

03-09-2005, 01:05 AM
Where is the ignition module located? Someone else told me that may be the problem. Thanks!

Ahhhh....the long dark path of TFI problems. The TFI module is located on your distributer where the vacuum advance canister usually would be. It requires a special socket to remove (most of the time) and that can be had for $4.99 at any Auto Parts store. It costs around $30 and is well worth just swapping out whether you need one or not.