Hi,

I'm working on my father's '89 F150 with the 300 I6 and manual. The truck initially starts on the first try, then runs for about 30 minutes or so, longer if the weather is cooler. The engine runs smooth and strong during this period.

The truck will then surge slightly before dying.

When attempting to restart the engine, the engine will occasionally turn over and shudder. Other times, it will not turn over at all. Either way all the dash lights come on as normal.

We've tested and/or replaced the ignition module and coil. The starter relay, starter, plugs, wires, cap/rotor, and battery are all new.

I've worked on cars most of my life and never seen one that will run so long and die at such a consistent time, so I'm a bit baffled as to what could be acting up.

I would appreciate any advice anyone has.

Thanks!

 

Typically, this would be the Ignition Control Module on the front of the distributor. When it gets hot, it no longer reads anything. It cools off and everything runs again. If you tested it, it probably would test good if it wasn't hot but it will fail under the hood with a hot engine. I've also seen the ECM die like a clock because of a bad circuit that overheats on the circuit board. If you've replaced the Ignition Control Module, take a smell of the ECM. It will smell burnt. I think yours might be in the right kick plate or it's behind the glove box- can't remember which. NAPA should have one that is a direct fit and programmed for you're truck. You need to take the old one with you.

 

Yes, change the ICM. Common problem.

 

Thanks for the suggestions. Since the ICM tested good(and it was heated during the test), I'll try to test the ECM and see how what happens. It's certainly an odd situation.