93 Ford fuel/line/tank issue

JonTCD

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New member, first post. I picked up a 93 F250 that's been in Massachusetts all its life, luckily the owner soaked it with a mixture of linseed oil, motor oil, and mineral spirits each year, its rust free which is like a unicorn around here. When I got it both tanks were full, it was running off the rear tank, I switched to the front just to make sure it worked, then switched back to the rear with no issues. I put Howes in both tanks, set the timing with a light and the power this has surprises me. When I switch to the front tank it will occasionally start bucking and /or increase RPM, it also doesn't like to start off the front tank, I swap to the rear and after a few miles its happy again. I haven't seen any water or contaminates in the filter. Im guessing its bad fuel or the line is sucking air. Not sure where to start.
 

subway

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yes it sounds like you are sucking air or have a restriction, does your fuel filter light come on?

i would do a close visual inspection of the fuel lines first. i had a stubborn air leak i eventually tracked down to where the fuel line passes through the sending unit on the tank. the fuel line corroded and cracked lightly at the base of the sending unit where it passes into the tank. not enough to be wet with fuel but enough to pull air in. that was a fun one lol.

how full is the front tank, these truck have a habit of breaking off the "shower head" that is at the bottom of the pickup tub and sucking air at about 1/4 tank. these pieces can also lodge and clog the inlet line.

if you dont see anything visually you might be opening up the fuel system to find it. if it were me i would pull the lines off the fuel selector valve and make sure it is switching properly. you can also take the opportunity to try blowing through the front fuel line to see if it is clear from the tank to the valve. fortunately you can actually pull the front sending unit if you need without removing the tank.
 

JonTCD

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The front tank is full, It has a replacement fuel filter so the light is not hooked up, there is a drain on the filter, I check it often and have yet to see any water or debris. I also cut the filter open to inspect it and it was fine.
 

Slicknik

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The shower head in the tank is probably no good and maybe the seal on top of the tank as well

You have air intrusion , so I would follow the fuel line from tank to filter and make sure your fittings are tight , replace fuel filter if the filter you have isn’t motorcraft or atleast (make sure it’s tight on there and make sure the fuel drain screw is tight ) replace o-ring on the heating element on top of filter housing

At the fuel pump/lift pump is another spot to check for fuel leaks (under alternator)


The Schrader valve works good for air bubble removal
 

JonTCD

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The shower head in the tank is probably no good and maybe the seal on top of the tank as well

You have air intrusion , so I would follow the fuel line from tank to filter and make sure your fittings are tight , replace fuel filter if the filter you have isn’t motorcraft or atleast (make sure it’s tight on there and make sure the fuel drain screw is tight ) replace o-ring on the heating element on top of filter housing

At the fuel pump/lift pump is another spot to check for fuel leaks (under alternator)


The Schrader valve works good for air bubble removal


Thanks for confirming what I was thinking. It shouldn't be that bad since its only when the front tank is on and that's not far from the valve.
 

Steve Turner

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near the front of the mid tank tucked into the frame rail

Been busy just had a chance to look into this a little more. When I switch to the rear tank I get a river of fuel falling onto the motor cross member. Tried looking but cant find where it originates at.
 

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