Recently purchased a 2011 Fat Boy Lo with only 680 miles on it. The fuel gauge read empty, so I filled up and it only took 2.50 gallons. Didn't think anything of it at that time. Ran through the gas and filled up when the gauge read empty again. This time it only took 2.14 gallons. So I logged the mileage and ran through that tank. Filled up when the gauge said empty. It took 2.50 gallons. Wrote the mileage again. It is averaging 36 mpg and only a 90 miles logged. If I am getting 36 mpg I should be getting about 180 per 5 gallons. However I am only putting in 2.5 a fill up. I never once got a fuel warning light. Can the gauge be bad, is there a manual switch (don't see anywhere) or is there a automatic switch that switches between left and right side? The fuel range right now says 188 with a full tank of gas, which would tell me that I have a five gallon tank. And yes if you asking yourself if I am new to bikes. Thanks for bestowing knowledge to me.

 

If you are talking about the fuel gauge that is located on the left side of the tank, you should know that they are notoriously unreliable. I never look at mine. Just click through your trip meter until you get to the fuel remaining display and go by that. When you get below 50 miles remaining, the trip meter will automatically switch from whatever mode you are currently in, to the fuel remaining mode.


My fuel remaining display usually reads 200 to 220 after fill up, but I ride without a windshield and that will make a big difference on your fuel mileage.

 

Something is definitely wrong with your fuel gauge if it shows empty when there is over 1/2 gas left in the tank.

Take it back to the place you bought the bike from and have it fixed on their dime.