1996 F150, 300ci six, auto, dual tanks. Truck will just quit running. Sometimes (rarely) it will start back up, most times it must sit for up to an hour, then will start right up. It usually does this after 5 or 6 miles. Other times though, it will run all day.
It does push fuel from the front tank to the rear tank, and I seem to have fewer problems when using the front tank. It also sometimes happens when I drive a few miles and shut the truck off. Run an errand and come back....won't start.....sits for an hour or two...takes right off.
I can hear the fuel pump engage, on both tanks, when I turn on the key.
Fuel filters have been changed, and one of the fuel pumps, (front tank I believe) has been replaced within the last year.
248,000 miles....first real problem I've had with this good old truck, and it runs great, when it is running.
I have also noticed the tail pipe is black on the inside. This has never been the case as long as I have owned the truck.
Any thoughts??

 

Do u have water in u fuel

 

No, this has been going on for some time, through many fillups, and now seems to be getting progressively worse.

 

O ok r ur gas lines clogged

 

I don't think so. It runs fine while running, and when it shuts off it is instant. No sputtering, no loss of power, just dead and coasting.

 

O but I don't think the black stuff in the pipe has to do with It. But idk if this can help but see if the exhaust is clogged up. I am out of possibilities

 

Check your fuel pressure both with key on engine off and with the engine running. fuel pumps are notoriously bad for this year. My front pump is going out, but I just don't use it anymore. If you haven't put a new fuel filter on in a while, slap a new one on there and check fuel pressure again if it was low to begin with. Has it thrown any codes???

 

Will do. Would a bad fuel pump allow gas to travel tank to tank, or is there a check valve somewhere that I am missing?
I also read somewhere that a bad fuel pressure regulator can return gas to the tank? $150 bucks and really hard to get to, so I thought I would get input from you guys first.

 

But my dad had a truck like yours and said that the black soot is normal

 

All I know is it went for 246,000 miles with a slightly white ish/tan coating on the inside of the tailpipe, and now it's black. Not using a drop of oil. ????