M813a1 fuel gauge ground?

[5tonman1971]

I was just wondering if there is supposed to be a ground wire on the fuel gauge going to the dash? I have 24.5 volts to the gauge the sending unit is newer. When I disconnect the single wire from sending unit the gauge stays on e when I was told it should peg to full when the wire is disconnected. So I'm trying to decide if to buy a new gauge or am it missing a ground? And there is a half tank of fuel

 

[doghead]

Try following the troubleshooting proceedure in the -20 TM.

Yes, the tank needs/has a ground wire.