HD Fuel Range Calculation Methodology

FROM:

https://serviceinfo.harley-davidson....en_US?nid=5014

I was curuous as to how the HD computer algorithm calculates "fuel range" after a fill=up. Good thing I checked. The HD methodology is NOT what you might think.

I went to the above HD service webpage and shown below is what I found. Ihave highlighted the 2 most interesting tidbits of information inbold red.

The fuel range display shows the approximate mileage available with the amount of fuel left in the fuel tank. The range display is only updated when the vehicle is moving.

Display Fuel Range: With the motorcycle turned on or in accessory mode, press the trigger switch until fuel range is displayed. The fuel range shows the letter "R" in the left side of the display. The calculated remaining distance (miles or kilometers) to empty is displayed, based on the amount of fuel in the tank.

Low Fuel: The fuel range is automatically displayed in the odometer when the low fuel lamp is on. The odometer displays "LO RNG" when the fuel range drops to 10 miles or 10 kilometers. The motorcycle is nearly out of fuel. Refuel as soon as possible. Refer to Specifications → Specifications → Capacities

.Turn Off Automatic Low Fuel Popup: With the fuel range displayed, hold the trigger switch until the fuel range flashes two times. To turn this feature back on, hold the trigger switch until the fuel range flashes once.

Reset: Resetting the low fuel warning lamp and fuel range requires sufficient fuel in the tank and an ignition cycle change (RUN-OFF-RUN).

Adding at least 7.5 L (2 USgal) of fuel allows the fuel range to update. The fuel range slowly updates over the next 50 km (30 mi) after refueling.

Battery Reconnection and Initialization: If the battery is disconnected and reconnected, the gauge requires approximately a half tank of fuel to initialize fuel range functionality.
Jim G

 

Mmm, I'm almost positive my bike updates the range the instant I turn the key on at the gas station, well before I ride off, and regardless of how little gas I've put in the tank. For I've minimally filled the tank before so I can more easily remove the tank from the bike for working on it.

Interestingly not mentioned is that when you're on "LO RNG" and get to 0, the miles remaining display blanks. I then have at least several miles of riding range beyond the zero range. Don't know exactly how many miles. Made the mistake of then reading the gear selector display as mileage range for quite a while once this way.

The tank is also calibrated to the bottom of the fuel inlet in the tank. If you work the stations gas pump and effectively over fill the tank, the increased range will not be included. It will simply display whatever it calculates for normal "full", for miles and miles on end. So I'll see something like 245 miles range for upwards of 70 miles or so.

 

Regardless of the miles my bike is able to travel due to the gas in my tank, I only have a 100 Mile bladder.

 

When you get to 0 range you really still have another gallon of gas in there. When my light comes on and says I have less than 25 miles left, I can only barely put 5 gallons in a 6 gall9n tank. It’s a cover your ads light is what it is.

 

"The fuel range display shows the approximate mileage available with the amount of fuel left in the fuel tank."

On mine it can't be trusted, it will show the approx. miles then after riding more than that number, it will update again. For example it might show 14 miles to empty, and still have over a gallon of gas. I zero the trip meter at fill up and when I approach 200 miles, time to start looking for a station.

 

What alerted me to the fact that the HD logic used is not what I epxected is that I posted recently about the fierce head wind I encountered on my return trip from the HD dealership 176 km away. After refilling the tank at tne end f the return trip, I noted that the "range" was showing as only 322 km, versus the typical 375 km, reflecting the bad headwind history.

However, yesterday I took my first ride since that dealership trip, in moretypical wind conditions, and after 80.7 km, I refilled the tank because I wanted a full tank for my next ride, which I knew would be a long one. The fuel tank accepted only 3.34 liters before shutting off the nozzle, so obviously the mpg for the 80.7 km was far better than it was for the headwind trip. However, when recording all the fill-up data while still at the fuel pump, I noted that the range was still showing as only 322 km.

Looking at the HD data in my first posting in this thread, I can see why:

"Adding at least 7.5 L (2 USgal) of fuel allows the fuel range to update. The fuel range slowly updates over the next 50 km (30 mi) after refueling."

This algorithm behaviour does limit the usefullness of the "Range" reading.

Jim G

 

For local rides, I typically fill up when the warning light comes on unless I am stopping for another reason. When traveling, i fill up at every stop…normally between 100-150 miles. I do the same when in a car except I go farther between stops…usually ~250-300 miles.

 

This is all very interesting. I have a 19 Heritage 114. I usually like to fill up when there is no less than 20 or 30 miles left to go on my range display. For the way that my friends and I ride (back roads, middle of nowhere most of the time), there is NO WAY we're going to be letting our tanks get too low and be in a sticky situation of not being near a gas station. We did that once with my wife's Sportster and it was quite stressful. Aside from potentially running out of gas, there was nowhere to pull off on a the twisty mountain road. Luckily we found a gas station just in time. Never again

For what it's worth I can tell you her 21 Heritage 114 and my 19 Heritage 114 are identical except for hers, purchased new has V&H pipes, installed with a HD tuner. Mine has a heavy breather with Rinehart pipes and no tuner. She can go about 10-15 miles further on a full tank.

Another bit of trivia, I found out though a conversation with my mechanic, the fuel sensor in my 09 F150 is the rear of the tank. I was seeing my DTE sometimes drop by 40-50 miles when I would park downhill. Not sure how all that works in motorcycle tanks.

 

When I refuel after the low fuel light comes one, I put in 5-5.2 gallons. The mileage range varies if I am pulling one of my trailers or not. With trailer, I refuel at 160-170 miles. Without trailer, I refuel at 200-210. I probably could go further, but usually need or want a stop at low fuel. When traveling, I usually carry a gallon of gas in my trailers, just in case.

 

Your trailercomments are interesting:

1. So the trailer(s) affect fuel mileage notoicebly? At what highway speeds do you generally pull them?

2. How heavy are the trailers typically?

3. How many miles have you done trailering?

4. Any incidents or discomforts attribtuabel to pulling the trailers?

I'm asking because HD is SO against pulling a trailer. But then too, they are against mounting a flag on the motorcycle - even though they sell flags.

Jim G