Fuel tank switch/valve problems

[dwjack]

This fall I replaced the passenger fuel tank and ever since the fuel gauge reads way past full but only for that tank. I made sure that the sending unit ground was good, it was so I figured the problem was inside the sending unit and planned on replacing it. Since then I have been using the driver side tank.

Tonight I went out to my truck and the gauge went way past full on the driver tank. I switched it to pass. back to driver but the gauge stayed there and it didn't sound normal when switching them. I could hear it running but not as long as normal.

I read that the valve isn't supposed to have power for the pass. tank. If the switch was bad would it automatically default to that tank?

[79BIG10]

You're right in that the tank should default to the passenger side when it' off. You may need to replace the dash switch itself. Sounds like it has gone out and needs replaced. Go to the dealer and get a new one.
On the auge recheck your ground sounds like a bad one.