94 F350 fuel tank selector switch

[sickcars]

Hey guys first time poster here.

I just picked up this truck and the fuel gauge was on E. I switched to the rear tank and it still said E. So I thought that both tankes were empty, I put $40 of fuel in the front tank and it still stays on E. The rear tank has about the same amount of fuel but both tanks wont move the gauge.

This truck has the 7.5 gas engine. Is there a possibility that both sending units are bad?? Or is there a way a bad tank selector switch could cause that gauge to stay on E??? I checked out the gauge and it seems to cycle and move fine with without getting stuck.

Is this a common problem or have you had this problem before?

Thanks