If my 2018 Fat Boy has a 5 gal tank, why even on empty, after it says I've used my reserve, can I only add 3.75 gal of gas?

Dilly7

 

Welcome to the forum from, well, Texas.

There are two reasons:
1. The fuel tank may not be completely empty. There's may be some fuel in it.
2. The fuel pump and fuel sending unit are located in the gas tank itself. They will reduce the overall volume available for gasoline. Think if you had a 5 gallon toilet tank and put a brick in it. With the brick in it, it will hold less than 5 gallons.

Also, there is no "reserve" in an EFI bike so what do you mean "it says I've used my reserve" ?

 

I'm glad to see that I'm not the only one with this problem. On my 2017 Heritage the fuel gauge is off by a quarter of a tank. The dealer replaced the gauge sending unit once and the speedometer head twice in the attempt to sync the gauge with miles to empty on the speedometer head. The dealer then told me that, by Harley specs, the fuel gauge can be off by as much as a quarter tank and if I still had concerns with this to contact Harley Customer Service. Fortunately it's in my favor. When the gauge reads empty, I still have a quarter tank left (fill up is about 3.5 to 3.75 gallons at this point). I just live with it and go by the trip odometer (miles driven).

 

Thank you. Your answer makes sense. Didn't talk down to me or tell me crap I already knew. And I thank you for that also.

 

I wish I was getting that kind of MPG... I get closer to 40-45MPG when I ride behaved.

SPEED SAFE, NICK

 

 

my lowrider gets 46mpg usually. i got 53 once on an all interstate road trip. I've ran my fuel guage down until it has read 0 miles to empty, htn it switches over to low and when filled up, it held 4.2 gallons. ( on a 5 gal tank)

 

I was getting 250 to 275 km to 25 liters of fuel...
Well, I didnt burn all of it, but there was two or three liters left in the tank when re-fueling up on a ride from Vancouver to Regina Sask this year and pretty much the same as five years ago when I took Mom and Dad on a ride Home.
2002 FLHTCUI,...6 spd SE and 95ci with SE 203 cams and tru duals this past year.
Rob

 

179.9 miles on the odometer....4.995 gallons in a 5 gallon tank. It died on me twice as I skated into the gas station. Thought for sure I was going to have to dial-a-friend. Wasn't paying attention to the little yellow fuel light until it was almost too late.

 

I've noticed a few minor fuel gauge problems with my 2018 FLHCS Softail Heritage 114. When brand new, it only showed 3/4 tank on the LED gauge. Dealership guy filled it up before I drove it away and commented that the gauge was off but would probably "self correct". Now (600 miles) LED shows full when really full. At about 400 miles, I showed 1/8 tank, got off the interstate, rode about 3 miles to a gas station and it was showing empty. Filled it up with 4.5 gallons. It appears that the last 1/4 tank or so is inaccurate. I now look at both trip meter miles and the gas gauge to make my judgement as to when to refill. Normally do so at about 150 miles ridden; it shows about 1/4 tank at that time. Checked mileage and got 47 mpg, just what HD claimed. I am not concerned about it now.