Oldsmobile/Buick Repair: Fuel Gauge 99 Park Avenue, gauge wires, fuel gauge

Question
The fuel gauge recently started going full to empty and back again.  Now the needle is pinned 360 degrees to the right against the pin which is just below the Empty mark.  Is this a bad connection (where should I begin looking) or sending unit, or something else?

Answer
Dale, try unplugging the sending unit connector(near the tank)
see where the gauge goes, if it doesn't move, try jumping the 2 gauge wires together, see if this changes, if it does, then it's your sending unit, if not, then it's your cluster panel.
                                 Good luck, Chuck