Fuel Gauge Ground Options

[David in VA]

Does anybody know where the fuel gauge grounds? I tested my sender and it seems to be working fine, grounds are connected to the back of the gauge and it reads empty with the key off and full with the ignition on. Never goes down though, I'd like the check the ground connection but don't know where it is.

Thanks
David

[toolguy]

3 wires at the sender. .. brn = frame ground, black = low fuel warning to dash light, green is the normal gauge wire to the gauge. . a red/white is the power at the gauge. .

For your gauge to always read full, my educated guess is your most probable cause is the float rheostat in the sender. Or the green wire is shorted to ground somewhere in the wiring harness.
As the float goes up and down there should be a resistance change between the brown and green terminals on the sender, which in effect controls the needle position of the gauge. . sounds like the green wire always has full ground potential. . [zero ohms resistance]
Last option = did someone rewire / reconnect the wires incorrectly on the sender unit plug??