1993 Caravan fuel gauge

My 93 Caravan, 83,000 miles, (one of the most trouble free cars I have
owned) has now developed a problem with the fuel gauge. Once in a while,
when I turn on the ignition, the fuel gauge stays on empty. The next time I
start the car, it behaves normally. Is it a ground, a sending unit, or what?
How do I diagnose such a problem?
Thanks
Bill

 

Once in a while,

or what?

Is it only the fuel gauge that is acting abnormally when this happens?
Does the radio work ok, and the rest of the gauges? I have a problem
with the ignition switch on my '91. Once in a while on start-up the
switch doesn't quite return to the on position from the start
position. This results in the gauges, radio, etc. not working, and the
airbag light staying on. If I wiggle the key back to the ON position
all is well. Try it.
On the other hand, it could be a problem in the fuel gauge circuit.
The fuel gauge sender is notorious for going bad, especially if the
van has high mileage. The sender is part of the fuel pump installed in
the gas tank.