Remove the gage panel and gently pull it out. Look for an inline fuse. Then replace the fuse. The gage should work. If there is no fuse or should it still not work then figure there should be a new fuel sending unit installed.The fuel sending unit is readily available at Boat US or West Marine. Look on the top of the tank. You should see a round plate with electrical connections connected to it.

1. Take off the electrical connections. Mark them right or left with masking tape.
2. Take a small screw driver or nut driver and gently back off the screws or hex nuts.
3. Pull the entire unit out. Cover the hole with a pie plate old piece of clean metal something and tape it down with duck tape. (Red Green will love you.)
4. Take the unit to the store and match it.
5. Coat the gasket between the tank and the plate with some form of gasket
sealer then reverse the process. Gage should work.