[AZKen]

Sounds like it passed those tests, so next question: What does needle do when ignition is OFF?
You can have a stuck float, stuck needle, bad sender or bad gauge.

Also: Why are you just now noticing that? What have you done wiring wise and what have you replaced recently? Please give part numbers and vendor name of any parts recently replaced. Give description of any work/wiring done.

1. Sending units are not voltage specific but require correct ohmage.
2. Gauge is voltage and ohm specific.