Okay so I have a 1985 Ford E250 with dual tanks. I have a switch up front and when I have the front tank engaged it works fine, though the fuel gauge is broken. But it pumps gas and runs fine, when I switch it to the rear tank I have a few minutes to drive (which I assume is just the fuel left in the line from the front tank) until it stalls out and dies. There is so much information but I cant seem to track the issue, has anyone dealt with this? Whats the first step?

 

If your vehicle is fuel injected, which I believe they started in 85, there is a fuel pump in each tank. It sounds like the pump in the rear tank is not working.
We check for power and ground getting to the rear pump inside the tank.if both are there the pump is probably gone into retirement. You can usually hear the pump run when the rear tank is selected, that would help provide a path to follow. The pumps only run for 2-3 seconds when the key is first turned on. If no rpm signal is received by the computer the fuel pump relay will drop out and open thereby preventing the pump from running. When you first turn the key on and the rear tank is selected , you should hear the pump run for the usual 2-3 seconds. Do you hear that?