Anyone seen this problem, and how do i fix it..?
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New User
Joined: Feb 2011
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Anyone seen this problem, and how do i fix it..?
I have a 1994 f250 4x4 std cab long box, 7.3 IDI turbo. I just bought it. drove it home.. and it quit running.. after 3 hours of investigating I found that 1 fuel is not flowing to the mechanical lift pump. when i disconnected the rubber fuel inlet hose there was suction in the hose.. to continue I cunnected a hose to a 5 gallon can of fresh diesel. I bled the lines after installing a new fuel filter/ water separator. Problem solved... no.. it starts and dies over and over.. then after playing around I disconnected the fuel return from the left rear of the intake and it starts and stays running.. so the problem i have is pressure building in the return system and not going to the tank, as well as no fuel flow to the lift pump.. I crawled under the truck and there are 2 tank switching valves... do they regulate the return as well? and wich one do i replace or how do i test them?
Cargo Master
Joined: Dec 2010
Posts: 2,123
Likes: 5
From: Fort Worth, TX
The tank selector switch controls both the supply and return fuel. Return fuel is put back into the tank it is drawn from to prevent overflowing of the tank not in use. To me, it sounds like the lines are clogged.
Try disconnecting the return and supply, then blowing compressed air through them to clean them out. See if that helps. Also check for leaks near the injectors. If you see any moistness, then I would start with replacing the O-rings in the return tees and the return lines in between the tees.
Try disconnecting the return and supply, then blowing compressed air through them to clean them out. See if that helps. Also check for leaks near the injectors. If you see any moistness, then I would start with replacing the O-rings in the return tees and the return lines in between the tees.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
If you have two selector valves, how many ports on each valve?
If they are six port valves, then the previous owner had probably a bed mounted tank plumbed into the fuel system.
Two switches, two valves, to control the flow to and from three tanks.
If there are two three port valves, then someone did a hack job replacing the stock selector valve.
If they are six port valves, then the previous owner had probably a bed mounted tank plumbed into the fuel system.
Two switches, two valves, to control the flow to and from three tanks.
If there are two three port valves, then someone did a hack job replacing the stock selector valve.
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