Ok guys I need some help. My 99 F-150 5.4 runs like brand new and then completely shuts off going down the road or sitting still. Put it in park, turn the key and it cranks up like new then does it again just down the road. Anybody have any idea what this is? No sputtering. Just perfect or nothing.

 

If it completely shuts off, no sputtering, then it sounds electrical. What kind of, if any maintenance has been done? (battery, alternator, etc....) Possibly a bad ground or Batt wires?

 

Yeah that is sorta of wierd?????? Can you give a little more info. On how anything else?

 

Dont think its batt. alt. or ground because it never loses radio, lights, etc.. Not sure. I bought this truck new and have always done everything myself. 163,000 miles. Because of the perfect or nothing I am lost. I am sure its electrical but no check engine light or anything that gives me a clue. I did read in my manual that it will shut itself off in certain situations but I see or feel nothing obvious.

 

So the entire truck doesn't completely shut off, just the engine dies? i.e. your radio is still on but the truck stopped running?

 

yes exactly.

 

I'm kind of at a loss for this one, have to wait for some others to wander through here. Jbrew, bluegrass? Any ideas?

I'll ask the obvious, you've changed the fuel filter? Not sure how you test the fuel pump, but I'm guessing that is OK? Just because there is not CEL, there could still be some "soft codes" I believe. Might not hurt to try and get a reading see what is there.

 

ok. Thanks for the feedback Jester.

 

double check your fuses and especially your relays in the engine bay, and thier connections.

 

When you restart do the gauges sweep? Do you have any modifications done to the truck?

JMC

 

Well im going to start by thinking the relays for the ecu????? This is a long shot.

 

put a cold damp cloth on top of your distributor and run to see if your distributor is getting hot.

 

99 5.4 doesn't have a distributor.

 

Still need to know if the gauges sweep on restart. Becasue if they do it is a sign the the PCM is resetting so it is loosing power or has a faulty ground. If not it is one of the critical sensors that is going out and killing the engine.

JMC

 

How long has it been since you pulled the cables off the battery and wire brushed them?

I'd get one of those battery post/clamp wire brushes and give them a good scrubbing... If it still does what it does, then at least you know you have good contact at the source..

Good luck!

Mitch