sender unit

[Egoreno1toy]

ok, gauge is pegged at 3,I've checked harness to gauge when I ground harness,gauge goes pass empty.Now I have cleaned ground wire from sender under car and touched a known ground and I get no gauge movement. Does that mean sender is bad

[169INDY]

Yup.

a Open or infinite resistance in the circuit Pegs the Dash gage. (F)
a Short or direct ground (0 Ohms resistance) in the circuit Sets the Dash gage (E)

If I am understanding your troubleshooting steps, I think your Sender wiper/variable resistor is bad or the connection to the pin terminal has come unhooked.

[Egoreno1toy]

Yes,gauge moves from past F to past empty during tan wire grounding test. after plugging back in tan,cleaning wire from tank strap and grounding I'm getting no movement off F. I'm guessing bad sender or connection of ground near sender