fuel tank sender

[erice]

i've got an older sabreline, one of the fuel guages is not reading properly. with tank full, showed about 1/2 full. ran tank to about 1/3 - 1/2 full, showed about the same level. what do i look for first?

[jleonard]

Check the wire(s) at the sender first, make sure it's got a good connection.

[loubennett]

I agree with jleonard, it's most likely a loose or corroded connection in the wiring between the gauge and the sender. You can test the whole circuit by disconnecting the wires on the back of the gauge and measuring the resistance of the sender. The guage will have 12 volts connected to one terminal and the sender connected to the other. Disconnect the sender wire and measure the resistance from that wire to ground. Assuming yours is a standard American sender it should read 33 ohms when the tank is full and 240 ohms at empty. For half full you should see about 140 ohms. If the resistance is high proceed to check the connections. I recently had a fuel gauge problem and was not looking forward to removing a large section of the cockpit sole to get to the top of the fuel tank and check the sender. I checked from the gauge end and the resistance reading match the amount of fuel in the tank. A trip to West Marine for a new gauge and the problem was fixed in less than an hour without major surgery to the boat.

[RobS]

Do you know if you have a capacitance sender or a float style sender?

[erice]

i don't know, but i'll try to find out this weekend.