Fuel Sending Unit

I have an '84 Southwind and my fuel guage isn't working. How do I test the sending unit? I checked the ground on the unit and it is good. Any suggestions?

Remove the wire from the gauge and ground it. This removes the sender from the circuit to ckeck the gauge first. The gauge should peg the needle. Ground it at the tank so at the same time you will be checking the wire from the gauge aft. If good then remove the sender from the tank. Use a analog ohm meter to check the resistance of the sender as you move the float arm up and down. Using a digital meter is possible but most do not react quick enough to get a decent reading. Double check the ohm requirement of the gauge. A common "unversal" is 33 to 240 ohm.

Check to see if your float still floats!!!!

I just went through getting the wrong sender for my X55 Dunphy. The gauges are Stewart Warner and they typically use the 33 to 240 ohm sender. I had replaced it several years ago with a "universal" which didn't fix the problem. Bought another "universal" and it still didn't work. I then took the gauge it self to Pat Powell who repairs S/W gauges only to discover the gauge was a 30 to 0 ohm!! He had no idea why they had such a odd gauge in the boat. Usually the 30 to 0's are military but lucky for me there were a couple of years back in the 50's that Chevy used them so I did find the correct sender.