How to Troubleshoot the Fuel Gauge on a Jet Ski

A fully functional fuel gauge is a must for any jet skier. The gauge is just one part of a system that measures and displays the fuel level in the tank, so you will need to check a number of different components and sets of wires to troubleshoot it. Fuel gauges display readings taken by a device called a sending unit, which is located in the fuel tank and transmits the readings by wire. Once you diagnose the problem, replacing the broken part is a cinch.


1) Check the fuel gauge’s positive switch. Remove the shroud so you can access the dashboard instrument connections. Strip the ends of a known good wire with wire strippers. Locate the ignition switch and fuel-gauge terminals, and use the good wire to connect them, ensuring the copper ends have a solid connection with the gauge and the switch. Turn the ignition to the “On” position. The gauge will display the correct reading if the positive wire from the switch to the gauge is faulty.

2) Check the fuel gauge’s ground wire by connecting the “Gnd” post to the jet ski’s chassis using a known good wire. Turn the ignition switch to the “On” position, and if the gauge reads correctly, the fuel gauge’s ground wire needs to be replaced.

3) Check the sending unit’s positive wire. Find the gas tank and the tube on top of it with two wires leading out of it; this is the sending unit. Connect the sending unit’s positive terminal to the fuel gauge’s post labeled “Sndr,” and turn the ignition to “On.” If the gauge works now, then replace this wire.

4) Check the sending unit’s ground wire by connecting the ground terminal of the sender to the chassis with a known good wire. Turn the ignition to “On.” If the gauge works, replace this wire.

5) Check the sending unit’s float. Remove the sending unit, and tilt it up and down, listening for the float moving up and down. If you do not hear the float, the track may be warped or the float may have broken loose. If it slides up and down, attach an ohmmeter to the positive and negative terminals of the sender, and slide the float up and down. The ohmmeter should show a change in resistance as the float moves up and down.

6) Check the float’s magnet. Open the sending unit, and pull the float out. If there is no magnet in the float, it has broken loose and is in your gas tank. Slide around a metal bar inside the gas tank to pull the magnet up, and secure it in the float.

Extra Tips:

* Never work on with the fuel system near an open flame.

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