hey guys i have to rack your brain,

1989 FordF-250 351W ZF-5 4X4 Dual Tanks

Both pumps in the tanks are working. High pres. pump is working front sending unit might be bad driving down the road it bounces all ovr the place if i top off the front tank the gauge reads E then i hit a bump it goes to full and if i hit another bump it could go anywere.

Rear tank pump is good can hear and feel it hum for about 1-2 sec. then shuts off sending unit seems to be fine.

Question number one i can switch between the front and rear tank the gauge switches but it seems to till run off of the front tank. i have owned the truck for three months now rear tank has been full for the past 2 and i have ran with the switch on the rear for the past 3 weeks...I relize that the only way to change tanks is the fuel pressure moves a a valve in the selcter correct? can i pull it apart and fix this?

Question number 2 if i were to take the selcter "valve" off completly could i run the to "input" lines into the "input" line for the Hp pump and the to return lines to the return line would it be ok? i know my switch is working right the front tank only runs when its turned to the front tank and the rear only runs when its switched to the rear.

so if the hp pump doesnt "suck" fuel very well why is my truck running with it on the rear tank and it only pulls fuel out of the front.

i would just put a bronco selector valve on but i love my dual tanks (when they work correctly)
<!-- / message --><!-- sig -->

 

Sounds like you need to replace the valve. You don't want to tie both tanks together at once. Too risky that you may overfill one tank from the other.