Hands like Houston54 will already know this, but I just found out the hard way and thought I’d share.
My gas gauge was working well, but a month or so ago it started reading OK at full, between 7/8 and 1/4 of a tank it would go to over full (pegged), and then back to OK at <1/4. I did all the usual searches, check ground (my truck has kick [censored] grounds now), continuity, etc., including pulling out the sending unit and hooking up an old one I had to see if it was that.
Both sending units read OK in my hand when I moved the float up and down, so I chased wiring. I jacked with that stuff for days until I finally broke down and bought a new gauge out of frustration. Solved the problem.
I believe that I moved the float of the sending units too fast when I tested it, making me skip a bad spot in the winding of the gauge. I’ve seen it happen with window motors, but I’m not sure if it happens to a gauge. If that theory is out in space, one of the guru’s will probably set me straight.
Anyway, the directions in most manuals work well for testing, but I recommend that during the sending unit test, you test it in “increments”.
