My sons 89 f150 started hard last week and died while driving after about 10 minutes. got there after 10 minutes and it started no problem. Drove it for about 5 or 10 minutes it died again. waited another 10 min., it started and I drove again. happened 1 more time before we got home. I replaced the coil and ignition module, but it still dies after it warms up? Any ideas.

 

When was the last time the fuel filter was changed?

 

Fuel filter would be my guess as well, but if the coil & ignition module were aftermarket (other than standard, etc.) they could easily be bad out of the box as well.

 

Didn't those have an issue with the fuel line/exhaust heat causing a vapor lock? I thought I read something about that one time. Idk, just throwing that out there.

 

Yeah, I seem to remember that. Didn't Steve tell someone that recently in the pre-97 forum?

 

only had the truck fo a coupe months, therfore not sure the last time the fuel filter wa changed. Today I checked the fuel pressure. Started and ran at 42psi, strong, then the pressure slowly started dropping until it died at 22psi. i restarted it several times and basiclly the same thing happened.
When I tried to restart right after it died, it had 22 psi, but wouldn't start. I had to wait a few minutes each time to restart it, but it would start and run for 5 or 10 minutes. Is this the pump or filter???

 

Probably the filter. I would try the filter first anyway as it is a normal maintainence item and is much cheaper and easier to change.

If you hadn't come up with the fuel pressure thing, I would have told you the stator in the distributor was bad. That and the coil which you already replaced are common things to cause this vintage Ford truck to act just as yours did.

 

Given the fuel pressure info, I'd say filter for sure. If it is backing up that bad you might want to run some fuel out with the filter off into a jar. That would flush the line before the filter and show you what kind of junk is in there. Just be careful.

 

Thanks, I'll give it a whirl.

 

Masseyman called it, I only added the flush part.

Don't run alot of fuel out, just enough to be sure it's clear.

Good luck and post your results.

 

Changed the filter, no luck. Pumped fuel into a jar and it looked clean....but, I found an injector leaking. The one all the way in the back by the pressure valve. If I spin it I can make it leak and stop. I can here when it leaks. Do you think this was the problem the whole time?
Regardless, I guess the o-ring is going to have to be changed. Looks like the whole fuel rail has to be removed, right. The throttle body too I'm guessing.

 

Has he had the truck a long time and it just started doing this, or is this a truck he just acquired?

FWIW, if he recently ran the tank very low or dry, that could have pumped a bunch of gunk from the bottom of the tank into the fuel system

If it turns out not to be fuel related, another thing to consider is bad catalytic converters. When they go bad, the motor will run real weak when hot, and may die and not restart. This usually comes on gradually and gets worse.

 

Changed the filter, fixed the injector leak no luck.
Switched tanks(front to back), still did the same thing. Switched the pump on the frame rail, still does the same thing(this pump was not new though. It came as an extra with the truck) Put the original pump back on and now I'm not gettig any fuel pressure? How can I tell if this is the pump in the tank, on the frame or could it be the regulator or inertia switch????? HELP

 

If you just lost all fuel pressure after starting to work on the frame rail pumps, I would look there, ie the wiring and connections and such.