I have a 2004 F 250 Super Duty 4x4 6.0 Diesel with 120,000 mi on it. I took it to the Ford Dealer last Friday and had the oil changed and the Rotors turned. While there they had to change the oil filter cap back to the original Ford cap. Saturday morning when I went out to start it, it seemed different. When i came back out after a minute or two I noticed a little fluid under the Passenger side front. Monday It ran a little longer and when I came out there was a steady stream flowing to the ground. Same on Tuesday, while it was warming up it ran rough as a cob. Once it is warmed up it runs great no leaks great power. Now I have to tell you I live in Phoenix AZ where the temp was in the 40's at this time. the dealer says it will cost about 1500.00 to fix some valve that has to do with a water separator. I have two mods on this truck and they are 1. 5" Banks turbo down and a cold air intake system that I keep very clean, i have 2 filters that I rotate. Any help will be greatly appreciated.

 

You're positive it's fuel leaking?

That was a good move putting the Ford oil cap back on, but it shouldn't have any effect on the fuel leaking. Can you tell where it's leaking fuel from? Probably just an o-ring that needs replacement, but hard to tell without knowing where it's coming from.

 

I got under the front and could see nothing wet except for an inline on a line going to the tranny. Nothing else seemed to b e wet at all so I have to say it is coming from the top of the motor. When I t leaks it seems to be passenger side just in front of the axle. As I stated before it runs like on 3 cylinders but once it warms up a bit it is fine, smooth you could stand a quarter on edge. I will look tomorrow to see if I can find it.

 

You could also check all your banjo bolts to make sure none are loose.

 

I am very sure it is fuel, my mileage has gone way down. I can't see anything underneath that looks like its leaking. It has to be coming from the top somewhere, I won't be able to tell anything more until this weekend when i start it when the sun is shinning so I can see more so I will write more later. If you have any other ideas let me know, i worked on gas vehicles for many years but not much with these so I need all the help I can get right now.
Thanks guys.

 

Well fuel comes from the pump on the rail, up to the fuel filter housing on top, and then two lines from the filter housing, one going to each head. Only so many places fuel can leak from up there...

 

I had a mystery leak when mine was cold and it turned out to be that POS hose clamp on my EGR cooler. Because it was kinda clear, I thought it was fuel.

 

have you checked the fuel pressure regulator on the front of the fuel filter bowl? Very common leak. And cheap and easy to fix.

 

Thanks to all that have answered, you have given me good places to look at and that is my job this weekend, yeah but guess what; it doesn't do it any more now that doesn't mean it fixed itself but it makes me lean towards a fuel pressure problem on Start up. The person who owned this truck before me should be hanged for the lack of maintenance he had done. What a waist of a good truck, I am glad I bought the power Train Warranty when I bought the Truck, Rear main, Seal, Transfer case and I need to install new Glow Plugs to go with about half a dozen other little things.Unless Diesel goes above $10 Its mine for the long haul, it has possibilities. Thanks again guys and if you think of anything else let me know.