Ok,
Both of mine work, but what I'm looking at is, my gauge is 6 volt,with a reducer from 12.
When I fill up the gauge stays on full until the level is almost down to half tank, before the needle moves. Then it will bounce around between 1/4 and 3/4 until fuel is at half tank, then it stabilizes to 1/2.
Is this because of the reducer, or maybe I have a larger OHMS sending unit?
This is not a pressing issue, because I can still drive, and not run out of fuel.