Locate the sender wire at the tank sender unit and ground it with the
key on. If the guage pegs, it's OK. The tank sender unit is probably
failing. Your gonna have to find it and remove it. Senders are generally
cheap.
JR

Wm. E. Fletcher wrote:
28 ft. Wellcraft, Coatal, 1989 with low hours. Have some gauge
problems. temperature gauge problem solved with new wire from sender.
Recently noted erratic fuel gauge. It would show no fuel at one time
and then 3\4th. fuel , then 1/4 fuel, etc. I know that there was about
30gal. in a 200 gal, tank. All the connections to the gauge look fine.
Where is the problem apt to be?. Is there a sensor or a float that
indicates the amount of fuel in the tank? Is it a wire? How to test! I
would hate to run out of gas 20 mi. out in Lake Erie The fuel tank is
sort of buried under the aft deck. I cannot see any gauges, wires or
anything leading to the tank. Help,please.!Bill Fletcher