I do not have a front tank. There is only one line that goes from one port to the other that connects both ports on the selector valve. Once I removed that line from the selector valve there was some gas in that line and coming out of one of the ports on the seletor valve. Should there be gas coming out of the front tank port when I have the rear selected? Would this tell me that the selector valve is faulty?

 

How does the selector valve work? Does it cut off one tank from pumping gas to the engine? Or does it just junction the two lines together and there is no switch involved?
Does the switch turn on the correct pump in the fuel tank? and turn the unused pump off?