In article ,
says...

I would LOVE to have a Cessna with a fuel guage that was accurate to +/- 10%.
On every Cessna I have ever flown, the fuel guages were best described as
semi-usless crap. Do I look at them? Yes; because in-flight they are your
only
direct evidence of remaining fuel. Do I trust them? No!



One little trick for Cessna drivers -
I've observed on many of the earlier 172's and 182's the fuel gauges are on
the same electrical circuit and fuse as the electric turn coordinator. If your
gauges are pegged at empty, try a few shallow banks to see if the TC is alive.
If not, and if your calculations indicate you should have fuel, you may
consider a simple (and rather common) electrical failure. On the other hand,
if the gauges are on 'E' and the TC is alive, you may want to consider getting
back to terra firma. Your mileage may vary - check your specific airplane.