fuel gauge always reads full

[Coopons]

Ok guys and gals, I have a 1996 F350 ccsb with a 7.3.
Rear fuel tank always reads way pass full does move until I switch tanks then it reads as it should
Tried a spare sending no dice. I verified that it worked by checking it before I pulled from donor truck
Any one have a wiring diagram for the tank wiring?
Will a fault tank selector valve cause the gauge to not read correctly?
The valve does switch back and forth from tank to tank

 

[IDIoit]

1/2 the time ive had issues with the tank readings, its been the fuel switch valve.
so it most certainly can.

reading full is a ground issue.
reading empty is a feed issue

 

[Coopons]

awesome thanks for the quick reply I'll check it out tomorrow and give an update

 

[Clb]

And then go **** on Henry's grave
My front just stopped working, at least it's the easy one...