There are four connections on the fuel gauge itself. The connections are listed below.

1) +12V when the key is on. That connection can come from the +12V connection on any other gauge as they are simply daisy chained from one to the next.

2) - Ground. Same thing -- gauges are grounded by daisy chaining them together.

3) Light -- same thing. The light terminals of each gauge are daisy chained.

4) Send -- this is a wire that runs back to the sender in the fuel tank. The sender is nothing more than a 33 - 240 ohm variable resistor. There are two connections on it, the sender wire going to the fuel gauge and ground. Above is a generic wiring diagram -- ignore wire colors as they likely will not match what yours are.

Turn your key switch to the on position, note if there is movement in the gauge, most gauges will move even if the fuel tank is empty or the sender is not working. If there is no movement, you can leave the switch in the on position; locate the fuel sender located in your fuel tank, usually it is under an access panel near center or aft in your boat deck. You should find a pink sender wire and a green or black ground wire at your sender. Using a jumper wire, connect the ground to your sender wire while watching your fuel gauge, it should peg to full. This quick test, checks your sender wire, sender ground all the way to the gauge. If your gauge pegs to full, change your fuel sender. (Note, be sure not to change your sender with a full tank, as fuel can flow from your tank with sender removed)

If your gauge does not move to the full position with the sender wire grounded, you could have 1 or more of the following problems.

1)    No ground at fuel sender, fuel tank not grounded (check for proper grounding at fuel tank)

2)    Fuel sender wire damaged or corroded, possible open wire from sender to gauge. A quick test at the back of the gauge could verify this. (check for power 12v at back of gauge with key on, either a red or purple wire. Check for a good ground at back of gauge in the negative black wire) if you have good ground and power at the gauge, simply ground the sender wire at the gauge, if the gauge does not move, replace gauge and retest.

3)    If the gauge pegs with above test, you have possible wiring issue between the gauge and sender, correct and retest.

Note: when testing fuel systems, do not give 12 volts to any part or the fuel tank or sender, also note, if you do not feel qualified to check your fuel gauge, please consult a local technician for these repairs.

If you are changing a fuel sender, always check for leaks, fill your fuel tank and check the area for fuel leaks. Consult the installation instructions of your fuel sender before attempting to change your fuel sender or gauge.  

  Tools required:

·          Test light, voltmeter

·          Jumper wire

·          Nut driver or suitable socket and ratchet

·          Wire strippers and crimpers

·          Screw drivers, Phillips and slotted

·          Misc. wiring and connectors