Is my lift pump dying? my truck defuels and refuels the engine
 

alright boys its been awhile but I need help fast. My truck has been cutting out bad at idle almost like air in the system but it smooths out and comes back at random this was stock fuel settings. last week I turned up my pump a few flats and it ran awesome but the random missing out was still at idle give it pedal and it goes away. Well today while pulling my trailor and snowmobile it started cutting out while driving BAD, so i floored it and it cleared up but then got increasingly worse.. I held it to the floor for about 8 miles ( i coulda cried being that mean to her ;( ) but it was all i could do to keep it running.. it would run out of fuel then load back up, defuel,refuel,defuel,refuel all the way home.. I could tell because of clear exhaust out the stack then black smoke. it was awful .. help me guys!!! is this a lift pump going bad or what ?

Check your fuel filter, when was the last time it was replaced?
Also check the fuel lines. Someone just posted about changing their pump, and the truck wouldn't stay running, turns out there was a cracked fuel line that was sucking air.

Brand new filter and I filled it with ATF .. Lines are pretty decent .. Iv got the Pensacola kit , would sucking air cut out all fuel ?? Because it's seriously taking away all fuel then it will load back up after you hold it to the floor for about 10 seconds .. This is at 55mph also

Check the lift pump by putting a guage on the scrader valve- when running should maintain 6-8 psi, also shows pressure just canking- search "lift pump" for more data.

Not the return lines sucking air, the fuel supply lines. Check the lines from the tank to the pump.

Bad batch of fuel?
I'd run a double dose of additive.
Can you see or smell fuel?
How old is the IP?
I've had experiences when the engine would stall if I let off the throttle quick. David85 pointed out it's a worn fuel meterng valve. Some additive helped a little, but repair by replacement was necessary.

Edit: OHH and I had a VERY bad experence when I tried patching a small hole in my fuel tank with RTV until I got a replacement fuel tank. Yeah, bad idea! A glob of RTV was sucked up the fuel pickup and lodged itself in teh connection between the sending unit and the blue plastic line. That took a week to figure out. It would idle like a champ, but if you put your foot into it and created pressure/sucton in the supply line...the RTV would lodge itself good and seal off the line. And then the motor stalled. After sitting about 15 minutes, cranking it over and purging all air about 4 times a day for a week....yep, bdecided to run new supply lines and found that little bugger! If you drove around easy without too much throttle, it would go fine. Only cut out when you put your foot to the floor. Might be something to compare to?

SIDE TRACK (ohhhh look a butterfly!): KJLYPW has the Stans Headers!? Hey, if you get a chance...could you chime in on this thread? https://www.ford-trucks.com/forums/1...derations.html

Alright fellas I'll do some testing today but my ol g

Ol girl has original injectors and ip ..however it runs like a raped ape I just don't see how it would up and die so quick .. I feel like it's the pump but does my symptoms sound like that of a dying lift pump?

After freezing my butt off driving to work this morning, I thought of something else. I forgot to check the temp before leaving, but they measured a record 19 below a few miles from my house.

My truck started ok, but as soon as I was on the throttle, the fuel filter light went on. Luckily I got into work without a problem, but along with the thoughts of bad fuel as mentioned above, maybe you have fuel gelling issues? (don't know your location...)

Hopefully for me, it warms up some today, I have about an 1/8 of a tank, and that can't be good when its this cold! Gonna fill up and treat it on the way home.

And a last thought, check the oil for diesel. It could be a dying pump, with a hole in the diaphragm. It would be leaking into the engine and diluting the oil.

Yeah tecgod, it's cold here today. My Dad commutes to work through Granby, CT and the electric sign at the bank said -11 degrees F at 5:10 am this morning. Both his '03 7.3 Stroke and my 6.9 IDI started fine. Stubborn, but still got going. It's cold times like this I think about that fuel heater like F250HDXLT was talking about some time back. I remember clicking on his link and it looks like that heater wraps around the fuel filter. Pretty neat, I think I might try one... And I've been thinking about some type of 12v magnetic heater to stick on the oil filter overnight for a cold start. Warm oil moves easier than cold oil...

And no, leaking return lines would not make the truck die. They just make the fuel system lose prime overnight.

How many miles on the truck? I still say some additive would be a good start. Even if it doesn't solve the problem, it would most likely rule out poor fuel.

Alright and I dont believe its gelling because it ran fine for awhile and my temps were midway on the guage .. ill try additive

Engine temperature won't effect the temperature of the fuel in the tank, supply lines, and filter.
Though the underhood temperatures from engine operation will help keep the fuel filter semi-warm, the wind chill from driving 55 mph on a very cold day will help keep that fuel filter cold. The bracket helps shield the wind, but I don't think it gets "hot" enough for the cold fuel from the tank and supply lines to warm up much before it gets to the engine.
However, with my grille open without a cover and driving, mine doesn't have any issues. F250HDXLT had fuel-gel while driving, which is why he is considering that fuel filter heater. He's in Maine, it gets cold up there.
How cold is the outside temperature?

I had the same exact thing happen a last fall and it was the lift pump. Good thing there not very expensive

Check the lift pump volume. Remove the valve core from the schrader valve on the fuel filter, attach a piece of hose to the valve and run the other end of the hose to a container. I have used a water bottle. Disconnect the FSS wire from the IP and crank the engine for 10 seconds. The pump should produce at least 1/3 of a cup of fuel in 10 seconds, if not the pump is bad.

i just thought of another time this happened to me. Got a new fuel filter filled it with diesel 911 and filled the tank with new fresh diesel plus the rest of the bottle of 911. let her run for a bit and drove it. worked great ever since.