I have a 1999 f-150 4.6l 60,000 miles It died on freeway, just like you turned the key off. I waited about 20 minutes it restarted and ran fine. Drove about 2 miles and while at a stop light just died, and restarted after a short wait again. Any help appreciated. I have seen post about cleaning an iac does this sound like it? Where is the iac? Fuel filter replaced at 45,000 . thanks Rick

 

The IAC sounds like a good place to start. The 4.6L engines are also know to have deposits form in the throttle body and it could not hurt to pull the throttle body and clean it.

If your truck will not start right after it dies then I would suspect a condition called "vapor lock". You let the fuel lines cool down and the vapor in the gas line goes away and you can start the engine again.

http://autorepair.about.com/library/faqs/bl828.htm

If your truck does not start right away after it dies you can remove the gas cap and put it back on. Then try to start the engine again. I have heard vacuum can form in gas tanks and cause problems but I don't remember if it can happen to our F150's.

 

thanks for the advice I cleaned the iac and it hasn,t killed since, but now i am afraid to drive it anywhere too far away. But thanks again.

 

Oops, sorry I did not post a picture of where to find the IAC. Glad to hear you found it!

http://www.fordf150.net/howto/throttlebodyclean.php

Hope your problem is fixed.

 

WELL I spoke too soon It has been fairly cool here lately but today was very hot and it died on the freeway on my wife. After about a 20 mile ride in very hot weather, any other ideas where to look. I keep thinking a dealer would charge me a fortune to put it on a machine and still not know what it was. What would you guys do?

 

Does the engine start right back up after it dies or do you still have to wait about twenty minutes before it starts?

I would change the fuel filter and see what happens.

My best educated guess is that you have a weak fuel pump...

 

It was around twenty minutes again.

 

Fuel pumps usually have a check valve to keep fuel pressure when the engine shuts off. This also fights against vapor lock. It sounds like your fuel pump is not strong enough to prevent vapor lock in your vehicle.

http://popularmechanics.com/automoti...mp/print.phtml

 

Thanks again This seems to make sense to me. I'll change the filter and figuire on changing the pump, thanks rick

 

I've also heard of problems with the crank shaft sensor getting hot and causing the engine to die suddenly. It won't restart until it cools. Search for previous posts on this and you should find a way to troubleshoot the sensor.

 

I would try the filter, but agree with the other guys sounds like a weak fuel pump. If anyway possible you should put a pressure gauge on it to see if the pump is working right. I just went through the same thing with a 2000 Olds Alero it would run awhile then die when the pump cooled down it would start and run until it got hot again. When the pressures were checked it only had 40 psi it should have had 52-58 psi.

 

Interesting post about the crank shaft sensor...