Fuel Gauge diagnosis - help

[beckoning]

My '89 Sea Nymph 195 has an in-dash fuel gauge for the 20 gallon tank under the floor. It worked, but now it doesn't. The needle stays on full. I jumped the wires at the tank (center post on gauge sending unit and ground on the tank) and the needle jumped to empty. I checked all the connections at the gauge and they're tight. Is there a fuse somewhere I'm missing? What are the next steps to check? I'd rather check things before removing the sending unit in the tank.

Any step-by-step analysis will help.

 

[BonairII]

Re: Fuel Gauge diagnosis - help

Maybe a bad connection/ground somewhere.

 

[beckoning]

Re: Fuel Gauge diagnosis - help

I've checked all the connections and they are good. Can someone explain how the sending unit installed in the tank works? The sending unit has 3 wires: center of the sending unit (seems red maybe), side of the sending unit (seems black maybe), and pure ground connected to the tank itself. I'm color blind so getting colors exact is hard and the wires are really filthy. If I cross the 2 wires on the sending unit (maybe red and black), the needle jumps to full no matter how much gas is in the tank. When I remove the jumper, the needle returns to empty. In my August 3 entry, I said the opposite. I could really use some help with this.

 

[Silvertip]

Re: Fuel Gauge diagnosis - help

This is discussed over 100 times in this forum. Use the SEARCH feature for diagrams, descriptions, resistance measurements, and troubleshooting. The Search feature is described in the stickies at the top of this forum. It even uses the fuel gauge as an example.