My 1995 Ford F150 pickup has 2 fuel tanks. It is a fuel injected system. The overflow fuel is returned to fuel tank. When I am on the front fuel tank , the excess fuel is returned to the front fuel tank , but the engine sputters some. When I am on the rear fuel tank , the fuel returns to the front fuel tank and the engine runs smooth. I have had my fuel lines 'bleed / blew out' but still have the problem. What part needs to be replaced ? Thanks for any help !