ukjones

I have 2004 5.4L When ever I hit a hard bump the truck completly quits and I have to stop and restart. It will restart everytime no problem. I checked the battery cables and everything seems fine. What else do I need to check?

Thanks

firedawg182

You should have a fuel cut off switch that stops fuel flow in case of an accident. Normally if a large "bump" activates this you would need to push the reset button in order to restart your truck but it wouldn't hurt to check your connections just in case.

Is your check engine light on?

When it is running does it run smooth or rough, steady or jerky, sound normal or sputtery? Does it restart easily or does it take a couple seconds of cranking?

And, just how big of a bump are you talking about?

ukjones

The motor runs smooth all the time. I thought about the fuel cutoff but the truck starts right away with no problems. I think I checked all the connections near and around the fuse panel. The starter wires seem tight and the ground there too. Once i went over a speed bump in front of lowes going about 5 mph and it quit. Another time I hit a man hole cover going around 30 mph and it quit.

wde3477

Intermittent problems are among the toughest to find, because it will never act up long enough to catch it.

The immediate restart ability is what has me puzzled.

My first guess would have been a bad connection somewhere in your fuel, ignition or related power circuits, but it would seem that, especially after going over the manhole cover, the engine should have 'roll-started' off the transmission still being engaged when the connection made back up???? Or that it sometimes would be difficult to restart??

Have you tried to simulate/re-create this - such as bouncing or thumping on the truck in the driveway? Might help speed troubleshooting if you can make it fault at will.

Have to think about this some more....

ukjones

This evening I tried to re-create the problem by puposely going over bumps but it never has done it again. But I did notice that when I come to a stop the rpms seem to jump up and down for a few seconds...like it is about to quit but never does. Thought about getting a good fuel system cleaner...do you recommend any? Maybe the fuel pump is having problems picking up fuel. I have a quarter of a tank in a 30gal tank....I would think that it would be enough.

wde3477

Way back when fuel pumps first went into tanks, it was advised by an auto mechanic's publication to keep at least a 1/4 tank minimum in order to keep the pump properly cooled. Don't know if that still holds true, but makes sense.

But I digress - a 1/4 tank should be plenty and then some for this issue.

For your idle surging problem, suggest to inspect the Idle Air Control (IAC) - have a tendency to foul up and get sticky, at least on my generation truck.

It seems around here, SeaFoam is the most-often recommended fuel system product. I also like the Berryman product.

How's your fuel filter - that would be a more likely suspect than a fuel pickup issue.