I have a 1978 F150 with a stock 351m. It starts up fine but after around 10-15 minutes it shuts off. When I try to start it up again it hesitates and shuts off and won't start up. I think it starts up again when it has cooled down, but it does not over heat.

The truck has new ignition coil, ignition module, 2150 carburetor, fuel pump, and new fuel tank.

One thing I noticed last night is that I'm hearing clicking sounds getting louder coming from the valve heads as it warms up and then shuts off. Not sure if that has anything to do with the problem.

I plan on checking the timing as soon as I can, and see if the carb is getting any fuel after if shuts off.

Also, there is a vacuum port in the intake manifold, in front of the carb (not on it), that was plugged off. I'm not sure if it is supposed to be plugged or connected to the air cleaner bimetallic valve, as I've seen on some diagrams... The engine runs a bit better with vacuum port unplugged.

If any of you have an idea of what I should check next, please let me know.

Thanks

 

if your ignition module is new.....it could be your full pickup is sucking full of crud cutting off fuel. seen this happen.....once it sits the crud falls off the pickup and off you go. But if you've been driving it a long time and it suddenly came about i doubt its that......the modules will do that though if they are shot.....act up hot and once they cool down...off you go

good luck

 

Replace the pickup coil inside the distributor.