There are many reasons an owner might want to replace the fuel gauge on their Fat Boy. The reason could be as mundane as the old one has stopped working. However, for many riders, the reason will be because the old one just does not match the style you want on your motorcycle. Whatever the reason, if you are comfortable with tools and feel you can safely work around gasoline, there is no reason to pay the dealership hundreds of dollars when you can do it yourself in a few hours.
Move your motorcycle to a flat, dry surface. Ensure you working area is well ventilated to dissipate any fuel vapours.
Remove your seat(s). The rear seat is removed by twisting the bolt behind the seat counterclockwise. On newer models this is done with your fingers, but can require a bolt on custom or older models. Gently pull the rear seat back and up to remove. This will reveal the front seat bolts, which come off in a similar fashion. Gently pull the front seat back and to the rear.
Consult your owner's manual and locate the fuse box. Remove the fuse for the fuel pump. Your owner's manual or a chart on the fuse box cover should indicate which one to remove. Once the fuse is removed, start your engine and let it run until the engine dies. This will depressurise your fuel lines and remove any residual fuel from the lines.
Locate your battery, which was uncovered when you removed the seat, and disconnect the negative (black) cable. Depending on the model, you may need to use an open-ended wrench or a screwdriver. Wrap the cable end in a shop towel to prevent an accidental spark, which could damage to your finish.
Locate the fuel supply line on the left side of the fuel tank near the rear. Disconnect the fuel supply line from your tank by pulling down on the collar and pulling the line free.
Remove the screw from the rear of the fuel tank. The stock part requires a T40 Torx wrench, but custom models may use a bolt or Allen wrench. Locate the retaining bolt at the front of the fuel tank. Using a socket wrench and an adjustable wrench, remove the screw. Gently slide the tank back to reveal the fuel gauge connector.
Disconnect the gauge wiring from the terminal connector.
Firmly grasp the fuel gauge and pull up and away from the tank. Do not twist while pulling, as this may damage the wiring or tank. Discard gasket.
Connect the wiring harness to the new fuel gauge as directed by the instructions that came with the new gauge. Insert the new fuel gauge into the fuel tank using the new gasket. Reconnect your wiring. Re-seat and reattach your fuel tank. Reconnect the fuel supply line. Reconnect your battery cable. Finally, replace your seat.
This article is for replacement of the fuel gauge, which displays the amount of fuel reported by the sending unit. It does not address replacing the sending unit, which measures the amount of fuel remaining in the fuel tank. This article is also based on a 2006 Fat Boy. Earlier or later models may have slightly different procedures. Because you will have purged the fuel from your fuel tank, it may take longer than usual for your motorcycle to start while the fuel runs through the lines.
Working with gasoline can be dangerous and cause death or serious injury. If you have any doubts about your ability to perform these actions do not attempt them.