1990 f-250 fuel leakage problem

i have become aware there is a recall on what i believe is wrong but i called the dealer and says it expired in 2001. with that said, i am having a problem with fuel leaking down over my front fuel tank. this tank is not in use and have never put fuel in it. i believe the pump is bad. however i have realized that there is a cross flow problem. i believe unused fuel is returning to this tank and then somehow either overfilling and leaking or something else. i just removed the front tank today and there are 3 lines running into the top of it. 2 which i believe goes into the fuel pump and one by itself with some type of valve or something on the top of the tank. my question is can i run it without this tank being put back on and what do i do with the open lines?

There's a fuel selector valve mounted on the frame rail that is supposed to seperate the tanks. It is operated by fuel pressure acting on a diaphragm. What is happening is fuel is being pulled out of the back tank, and the unused fuel from the engine is being pumped into the front tank, which overfills it. The assembly is next to impossible to find, and if you can, it's $150. I had a friends truck doing the same thing. My only option at the time was to find 2 fuel filters that would take the place of the valve. We hooked up the rear tank pressure line to the engine pressure line, and the engine return to the rear tank return using the filters as an "adapter". This way didn't cause any fuel pressure or driveability problems what-so-ever. This may not make sense without pics, so I'll try to take pics and get the filter #'s for you.