I Hit a pothole in road and the truck shut off.I pulled off the road and found that # 30 fuse was blown.I replaced it, and as soon as the key was turned on it blew again. Thinking there may be a short on frame or chassis I jumped up and down on the back bumper,I tried replacing fuse again and this time it did not blow.The truck started and has been running fine since. still I don't feel safe taking the truck on trip or letting my wife drive it. I have owned truck since new. It has been well maintained and serviced. I just cant figure this one out? any Ideas would be greatly appreciated.

2001 f150 crew cab
4.6 liter v8
Bi-fuel package gas/propane

 

Have you looked up the fuse in your owner's manual page 192?
It will suggest why the motor shut off.
Look at those areas for a wire short to ground.
Only you will see where it is.
Good luck.

 

Yes, have tried looking at the harness top to bottom especially those devices on the #30 fuse like the pats , the pcm relay, dont know where the radio noise capacitors are though. Checked the harness going to the coils no visible shorts. Everything looks good. Could there be an intermittent short in the alternator or the pcm. But i dont think a bump in the road would affect those two as they are solid state and mounted with substantial protection from shock. Any other ways to locate a short other than refinancing my home and selling a kidney so i can afford taking it to the local ford dealer?

 

Attached to the heads, one on each bank.

No, F30 circuit does not go to either.

F30, in the factory as-built configuration, feeds the following:

Instrument cluster
PATS transceiver ring
COPS (w RFI caps)
PCM Diode in underhood fusebox, energizes PCM Power Relay in START/RUN

Since you have the bi-fuel conversion and it didn't come out of the factory that way, there's no documentation in the factory service manuals on it. Therefore, it is unknown if that conversion tapped into the F30 circuit. My bet is that it does.

Well, you could put a piece of heavy wire in there and wait for it to burn up, but that might be the more costly alternative.

Intermittent faults, especially a short circuit, can be particularly vexing as it's almost impossible to pinpoint the fault when it's not present at the time you're looking for it. There's a reason that what is left of my hair is grey (and it's not just from teenagers...), I've been doing electronics for almost 40 years.

Your best bet is to use an ohmmeter with a continuity test beeper hooked between the load side terminal of the socket for F30 and ground, then start wiggling and pushing/pulling on suspect wire harness as see if you can get it to beep. If you can, then it gets easier to find the intermittent short to ground. If you take it to a dealer, this is the most likely thing any tech would do after he's performed a visual exam.

 

Thanks for the advice i found the radio capactors and jiggled the wires around them while the truck was running. The wires sparked around the passenger side capacitor on the front of the intake and bam! The truck died and blew fuse #30. Got anew capacitor from ford ,replaced fuse. Looks like i am good for another 180,000 trouble free miles. It looks like the way ford routed the wires is very close to the block on the pass side and this allowed the wire to rub through causing the short. Cant complain too much . This is the only problem in 15 years, and an easy fix once you figure it out

 

That's for posting your final solution!

FWIW, the engine will run just without those rfi caps. However, anyone near you trying to listen to AM radio won't much appreciate their absence.

 

Glad you figured it out, other known harness issues are steering column near tilt pivot, and the harness for the O2 sensors rubbing on the Cat heat shield causing O2 and trans faults

 

None of which will cause F30 to blow, different fuse. See list of F30 feeds above.

 

This is a very strange thread. The OP is a new poster and actually LISTENED to the advice given AND posted the solution!

Thanks my66chevy and welcome. Come back and visit!

 

I wasn't implying that they were associated with F30.

Just simply elaborating on the topic of known harness issues in case it helps him or someone else using the search feature :thumsup: