When I purchased a 1989 Ford F-250 and I filled the front tank with gas. The front tank pumps gas to rear gas tank was overfilled and spilling onto the ground. Any clues on what could be the problem?

Unless someone previously worked on the gasoline lines and switching system, I would totally agree. The tank swithing mechanism is actually rather more complicated than it needs to be on these ford trucks. You have a helper pump in each tank and a main pump located along the frame underneath the drivers door are. Along with this main pressure pump, you also have the switching mechanism. There are supposed to be one way valves that would prevent just such an occurrence, but these valves can become gummed up and not properly operate over time. I believe this is what is happening with your particular truck. My recommendation would be to replace the the entire tank switching assembly with a brand new or factory rebuilt unit. Do not waste your money on something from a wrecking yard as you never know what you will be getting or how long it may last. Best of luck.

Hello Sam, I think you have a problem with your fuel solenoid valve that switches from front tank to the rear . I do know that Ford dealer has a recall on '93 F-150 like mine. I'm not sure about yours.