We are having trouble with our duel fuel tanks not working properly, the front tank is full but won't keep running on the front tank. It will run on the rear tank but it pumps the fuel to the front tank, causing it to overflow.

Has anyone had this kind of issues? and What did you do? ASAP please.

 

Sound like a bad check valve, and possibly a bad front pump.

 

What year? They're not all the same.