I've had the float arm cross the pickup tube and jam, making them fail to work.

As for the tank being grounded, no the tank itself doesn't need to be grounded persay. It's the sending unit that needs to be grounded. The sending unit has two wires going into/out of it.

Depending on which tank it is, you have either Dark Blue/Yellow wire or a Yellow/Light Blue wire, and a black wire.

To check for a bad ground wire at the sending unit, or bad gauge in the dash, use a jumper wire and connect the colored wire to the black wire, in the connector, then go into the truck and turn on the ignition to accessory; making sure the dash selector switch is on the correct tank for testing (Dual tanks).

If the gauge pegs, the gauge and the ground to the sending unit is good, and the sending unit is at fault.

If the gauge doesn't peg, take your jumper wire and connect the colored wire direct to ground.

If the gauge pegs, then you have a groud fault on the black wire.
If the gauge doesn't peg, you have bad wiring to the gauge, a bad selector switch in the dash, or a bad gauge.

Hope this helps.

 

Thanks for that catch. That's what I meant, but didn't say it correctly.

 

Going to check out the fuel gauge tomorrow, got the temperature gauge working the sender was dead, i looked down into the carb today i saw only a tiny trickle of fuel.