"Frank Taylor, Jr." wrote:

My boat was out of the water for about 6 weeks getting some repairs. Right
before I put it back in the water, I filled up the fuel tank (fuel at the
gas station is cheaper than at the marina). So far, I am sure that I have
burned at least a quarter of a tank but the fuel gauge still says full. I
also noticed that before the ignition is turned on, it rests at the empty
position and as soon as I turn the key, it immediately pops overk to the
full position and stays there.

Is there any way to unstick a stuck fuel gauge? I have found what appears
to be the fuel gauge sending unit on the top of the fuel tank and it looks
simple to remove/replace (three screws and some type of sealing gasket).
The wires seem to be intact.

There may be nothing wrong with the gauge circuit. Gas tanks usually
have a pretty big empty space built in to allow for fuel expansion. It
MAY be that you forced enough gas in to fill this space and simply
haven't used it up yet.

If you're sure that's not the case, try banging on the tank. It's also
possible that a slight overfill forced the gauge's float abnormally high
and it stuck there.

If banging don't fix it, disconnect the wire(s) from the sending unit on
the tank. The gauge should read either empty or full (I forget which).
Short the wires together momentarily. The gauge should read the opposite
(full becomes empty or vice versa). If there's no change with the wires
open/shorted the trouble is in the wiring between the gauge and sender
or the gauge itself; otherwise the sending unit's faulty.

Be VERY careful if you have to remove it - it could be below the level
of the gas in the tank so have rags and an extinguisher or two handy and
make sure all electric and flames are off. Most units comprise a simple
float that "adjusts" a variable resistor.

Good luck ....