1997 Ford F350 gas leak

RAY BOS

MEMBER
1997 FORD F-350
V8
4WD
AUTOMATIC
106,000 MILES

I have a 1997 f350 pickup w dual tanks, front tank was on with gas in it & wouldnt start, changed to rear tank & truck started. Tried front tank the next day & it started, since then it will not start while front tank is on.
Have been operating rear tank only for a month.
I assume the pump in the front tank is bad, although I have not put gas in front tank in a long time there is gas leaking out my front tank filler cap, my mechanic has drained the front tank several times and the tank wont leak for a few days but then it starts leaking all over again
My mechanic has GIVEN up! He does not know whats wrong with it, please HELP!

1 Reply

BMRFIXIT

MECHANIC
19,053 POSTS

Shuttle valve opens fuel return line to fuel tank when fuel pressure on shuttle diaphragm exceeds opposing check valve spring force. When pump is de-energized, supply check valve closes to maintain pump prime and fuel supply line pressure. I would be looking at the fuel drain back line, I would be thinking that it is split between the two tanks, and the excess fuel from the injector rail is part going into the front tank causing this back filling, check this out.