Coming home from work yesterday, my truck(1997 4.6/auto) suddenly just dropped off in power and then died. I was only 1/2 from home and was able to nurse it home by recranking over and over. Finally got to where it would crank up, then immediatly die.

I had replaced the fuel filter just a few weeks earlier, so ruled that out. Decided it was the fuel pump since I could unhook the fuel line on the front side of the fuel filter and turn the key on and very little to no gas was coming through. So bought a new fuel pump.

Installed pump and symptoms remained the same. Then I remembered about the "fuel cutoff switch" these trucks have and thought maybe it was that. Tried pressing the reset switch. Is it supposed to be like a breaker? Do you feel any click or anything when you push it? I ask because I didn't feel anything, didn't seem like the button moved at all. But after playing with that the truck cranked up and after struggling a bit idled fine. Reved it a few times also just fine.

Got ticked off for having spend so much on a new fuel pump, so I decided to put the old one back on and try to sell the new on Ebay or something(didn't figure I could get away with returning it). So I did that and the truck cranked and ran. Reved it some again, decided to take a test drive. Backed out of the drive fine, took off fine, got about 1/10th of a mile down the road and it cut out just the same as before. Got turned around and nursed it back home again.

So now I'm back to square one, except the truck will at least idle now. At least it did when I came in. I can even rev it up some and it be okay.

Only other thing to add is that the old pump would definatly run. I jumped straight from the battery when I had it out.

So could it be air in the fuel lines that just needs worked out? Could something be screwed up with the new filter I put in that just now showed itself? Really the pump? Any thoughts would be greatly appreciated.

 

so you put in a new pump and it runs fine..then you replace it with the old one and it's back to square one..hhhhmmm..put the new back in...check to make sure the fuel filter is in the right direction of flow..and start loking at the Idle Control switch and also for any vacume leaks(look behind the throttle body at the hose from the PVC valve)..seems funny the check light hasnt come on you might also look at your coil packs one may be going bad

 

Thanks for the reply TexfordD, I figured out the problem and it wasn't the fuel pump at all. It was the Mass air flow sensor. Since it seemed fuel related, I failed to check other obvious things first.

I have a cheap fipk that I don't recommend to anybody. It's an Air F/X by Pacesetter. It utilizes the MAF half of the stock air box by just clamping on to the small lip thats there. The one bolt on the one little bracket had worked loose and the weight of the filter pulled the MAF sensor loose in the housing. So I was getting in tons of unmetered air.


Apparently after installing the new pump and it not working I had noticed something didn't seem right with the filter and pushed it around a bit so that it wasn't as bad, but then after switching back to the old pump and going for a test drive it pulled loose again.

Anyway long story short, I'm a moron but my truck runs fine again...

 

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