Hi all i got a 1991 f250 with the 7.3L and duel tanks my problem is that i love having two tnaks but can only draw from one (i think) i normally draw prom my front then switch to the back if i need to but after i put a new bed on i now switch to the back tank and the fuel guage goes way past the full line. but i don't know if it is pulling from the rear.


any suggestions to test the valve? thanks tim

 

I would check the wiring for the sending unit from the rear tank. If it grounds out I believe it will read the way you are describing.