Persistent fuel leak

1991 f-350 7.3 idi leaking fuel around lift pump. It seems to leak only until engine warms up. Replaced hoses once and lift pump twice! I’m not sure where to go from here.

Try looking at the filter housing located directly above on the engine. It may leak there and dribble down on to the lift pump.

Everything above the lift pump is dry. It’s hard to tell if it’s the pump or a hose.

Are you talking rubber hose or hard line? What hose clamps are you using?

Clean everything off with hot water or brake cleaner. Start at the top then work your way down. Then run the engine and look for the leak.

Are you using a gasket on the lift pump? Torqued it down correctly?

Never-Have-I-Ether

I recommend this style clamp for fuel lines on hose barbs, they cost extra but they are worth it to me. Double check size I just grabbed a link for example purposes.

Other thoughts.

1) Coming down the fuel line between the lift pump and filter head is usually a small rubber hose used to drain water from the fuel filter bottom bowl. There is a finger nut under the bowl to open and drain. Perhaps that is leaking/blowing onto the the lift pump when cold or driving and pressure goes up. Leaks onto the lift pump and giving the impression the pump is leaking. Maybe re-route it to test.
2) On the bottom of the fuel filter bowl is a water sensor, perhaps it leaks till it warms.
3) On top of the filter is the fuel heater. It has a wire to it. They start to leak over time, but slowly and off and on at first. Some pull it and replace the o-ring, others delete it by threading the hole and putting a pipe plug in the hole.

Ditto on Clean off the diesel and look for it to leak.

Big Bart said:

1) Coming down the fuel line between the lift pump and filter head is usually a small rubber hose used to drain water from the fuel filter bottom bowl. There is a finger nut under the bowl to open and drain. Perhaps that is leaking/blowing onto the the lift pump when cold or driving and pressure goes up onto the lift pump and giving the impression the pump is leaking. Maybe re-route it to test.

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I think that this is a fairly likely place for the fuel to be coming from.

Everything is dry above the lift pump.

I’ll check that out next time I can get it in the garage.

never hurts to replace your pump anyways mine only cost 40$