6.0L Difficult to Start - Losing fuel Prime

[dpassarella]

Hi,

I have a 2004 F350 with a 6.0L Diesel. The truck has about 150K miles on it. It has had fuel injector problems in the past, probably because we don't run the cleanest fuel in it. (We get our fuel delivered to a holding tank that might get dust in it)

Lately, just about every time I start the truck, I need to turn the key to accessory on for about 10 sec, then off, then on again before the truck will start. It will always eventually start. I know the problem is that the secondary fuel filter housing is losing it's fuel prime. If I unscrew the cap and turn the key, the housing fills right up, then I can put the cap back on and the truck starts up after a few cranks.

Once the truck is running, it actually runs pretty good. I never have a stalling problem with it now. (I used to have a stalling problem before I changed the injectors, but now it is ok. This is why I have held off doing a balloon test)

If I shut down the truck for under 5 min, it will usually start back up without having to cycle the fuel pump. If the truck is off for longer, I need to cycle the fuel pump a few times before it will start. If I try to crank it before the fuel is primed, then I think air enters the lines after the secondary filter and I have to purge them by cranking for a while.

Any idea what causes this filter housing to lose prime? Could it be a check valve some where in the fuel system before the secondary filter that is not sealing properly because of dirty fuel debris? ( I had this problem in an air compressor that runs the same fuel) I checked the lines pretty good for leaks, and the truck never drips oil or fuel in the driveway, but I guess it could still be a leak before the suction fuel pump. (I don't think so however because the truck primes so quickly once the secondary fuel filter cap is off.) Something weird is that when I go to start the truck in the morning (when the engine is a little cold), it starts perfectly. Maybe the fuel is cooler and thicker? But then why dosn't the fuel drain when I shut it off at night?

On a hunch, I tried to clear the water out of the fuel pump. The first time i did this years ago, I stripped the drain plug on the water trap, so now I have to pull out what I believe is the water sensor to drain the water. When I last did this (after the starting problem began), what came out was pretty nasty. It looked like the sensor probes had corroded.

Thanks so much for any help!

[bondsman]

Try changing fuel filters. Put the new orings on and make sure you dab a little fresh oil on them. Could be a leak at a cap. Since you aren't seeing any leaks, that would be my guess.