Fuel Gauge adjustment?

[Mr_Canoehead]

...Should be able to get this data relatively easily just by fully emptying the tank and then making iterative resistance checks as measured amounts of fuel are added with the tank and bike level.

I once went through this exercise on my '10, see here. I was going to use a microprocessor to linearise the reading, however I couldn't do what I wanted because there was too much dead zone both near full and near empty.

That's was I was thinking - it reads empty today at what is really about 1/4 tank - if you modify the output, it will still show 1/4 tank when you sputter to a stop because you are just shifting the output. Better to just understand how far you can go when it starts flashing.

 

[Uncle Hud]

Agree with the Canoeheaded One. Seems like a LOT OF WORK to achieve something that can be simply handled through experience:

"Hmmm. Fuel gauge is flashing. I have roughly a half-gallon of fuel left. That will yield about 20 miles of travel. Perhaps I should seek out a gas station."

Don't look at your odometer and start doing math, because that will only increase the rising levels of dread and panic:

"Jeez-oh-Pete! Only 3 miles left in the tank! Couldn't possibly be a darker night, could it? Wonder if bears live around here?"

 

[RossKean]

I work on the assumption that there is between five and six litres of fuel left when I go to flashing mode. If I may be some distance before a gas station, I will reset the average kilometers/litre (miles per gallon) gauge so I can monitor the rate of consumption as well as the count-up distance. It can make a big difference if you are doing stop-and-go riding or blasting down the highway vs. a nice easy 80 km/hr ride on a secondary road. "Safe" distance could be as much as 120 km to as little as 70 km. (I actually ended out coasting into a gas station after 70 km on "reserve" this summer - highway ride, pulling a trailer, strong cross wind - (30 mpg))

 

[Uncle Hud]

70 km (42 miles) on reserve with that load at highway speeds?!?!

When my 2015 goes on reserve, I reset that screen and it returns to the usual "distance to empty" display -- which a US bike will display as around 20 miles. If I reduce speed and rpms, the distance to empty actually goes up a few miles before it begins to drop again. On a couple of recent trips, I've ridden until the distance to empty displays "LO" and still gone another ten miles (16 km).

 

[RossKean]

70 km (42 miles) on reserve with that load at highway speeds?!?!
When my 2015 goes on reserve, I reset that screen and it returns to the usual "distance to empty" display -- which a US bike will display as 20 miles. If I reduce speed and rpms, the distance to empty actually goes up a couple of miles before it begins to drop again. On a couple of recent trips, I ridden until the distance to empty displays "LO" and still gone another ten miles (16 km).

On the Gen II, the count-up odometer starts at zero with (on my bike) close to six litres (1.6 US gal) left. So, at 30 mpg, this is as much as 48 miles under these adverse conditions. I once did almost 70 (very careful) miles when I was surprised by closed gas stations along my route.

 

[Fred W]

Agree with the Canoeheaded One. Seems like a LOT OF WORK to achieve something that can be simply handled through experience:
"Hmmm. Fuel gauge is flashing. I have roughly a half-gallon of fuel left. That will yield about 20 miles of travel. Perhaps I should seek out a gas station."

Don't look at your odometer and start doing math, because that will only increase the rising levels of dread and panic:

"Jeez-oh-Pete! Only 3 miles left in the tank! Couldn't possibly be a darker night, could it? Wonder if bears live around here?"

To begin with, it switches to reserve at around 5 to 5 1/2 gallons of fuel used, as measured by what it takes to fill it immediately when it switches over. This based on my own experience with a 2005 and a 2014 bikes. Plus comparing with FJR riding companions and their experiences. If it was 1/2 gallons left nobody would give a shit. When its 1.6 gallons, which translates to about 60 to 70 more miles, its a bigger deal.
And unlike in your southeast or my northeast, there are places even in the civilized nation of the US where gas is sparsely available. Been there. Done that. Barely made it to the only gas station in range.

Its not really a lot of work. But knowing more closely how much further you can go can be crucial under certain circumstances. I dont see the downside of more accurate information, but maybe thats just me.

 

[Fred W]

...

Should be able to get this data relatively easily just by fully emptying the tank and then making iterative resistance checks as measured amounts of fuel are added with the tank and bike level.

I once went through this exercise on my '10, see here. I was going to use a microprocessor to linearise the reading, however I couldn't do what I wanted because there was too much dead zone both near full and near empty.

Just found your data. Didn’t see your embedded link initially.

It looks like the sending unit is at 125 ohms when the reserve mode is initiated. The bad news is it appears that the resistance of the sending unit jumped from there to the maximum resistance of 140 ohms with little change in gas level. That anomaly in the graph doesn’t make sense to me, but if true means there is no way to improve the low reading level.

I don’t care how long the tank says it’s full. Just wanted to delay the onset of reserve count up.

 

[Bounce]

"Hmmm. Fuel gauge is flashing. I have roughly a half-gallon of fuel left. That will yield about 20 miles of travel. Perhaps I should seek out a gas station."

Isn't it odd how different people react differently to the same situation. I have no problem running (rough) numbers in my head. But then I don't bother with M/Km conversions like Uncle Hud and RossKean so there is that. (JK)

 

[mcatrophy]

...

Should be able to get this data relatively easily just by fully emptying the tank and then making iterative resistance checks as measured amounts of fuel are added with the tank and bike level.

I once went through this exercise on my '10, see here. I was going to use a microprocessor to linearise the reading, however I couldn't do what I wanted because there was too much dead zone both near full and near empty.

Just found your data. Didn’t see your embedded link initially.
It looks like the sending unit is at 125 ohms when the reserve mode is initiated. The bad news is it appears that the resistance of the sending unit jumped from there to the maximum resistance of 140 ohms with little change in gas level. That anomaly in the graph doesn’t make sense to me, but if true means there is no way to improve the low reading level.

I don’t care how long the tank says it’s full. Just wanted to delay the onset of reserve count up.

The anomaly I can't explain. I was taking reasonable care during the process. I would have suspected some sort of stiction, except I got a reading partially up the step.

Because of the obvious limitations of the sender near full and (in particular) near empty, I didn't repeat anything as I'd learnt enough to show I couldn't achieve what I wanted.

Like everyone else, I know I've got several tens of miles when it starts flashing, simply rely on knowing how many miles it's likely to do. The "Range" gives something like 20-25 miles when the F starts flashing, and goes to zero when you still have 20-30 miles left, so is very pessimistic. I don't attempt to do Bounce's "hard sums" using the bike computer's mpg reading, I'm more likely in a near panic looking out for the next available fuel stop

, particularly if I'm in unfamiliar territory where fuel is sometimes hard to find.

For the record, the minimum miles after the F for each of my FJR's calculated from a few random samples from my MPG data:

2006: minimum 55 (maximum 77)

2010: minimum 49 (maximum 78)

2014: minimum 51 (maximum 69)

2018: minimum 52 (maximum 64)

Invariably, the minimums are during much town riding, the maximums in what I would call tourist riding.

 

[YummYam]

Just checked mine out and had one bar showing on the gauge having covered only 172 miles since fill up!!!

Squeezed in 3.65 gals giving around 47 mpg.

So that one bar showing means there is still around 3 gals in there!! Hmmph!

 

[RossKean]

Just checked mine out and had one bar showing on the gauge having covered only 172 miles since fill up!!!
Squeezed in 3.65 gals giving around 47 mpg.

So that one bar showing means there is still around 3 gals in there!! Hmmph!

Nice knowing that (on mine) I have ~1.5 gal (5-6 litres) of fuel and something more than 60 miles (100 km) available once the gauge starts blinking (with modest throttle management). If it happened at half a tank, I'm pretty sure I would adjust the float or replace the gauge.

 

[YummYam]

Just checked mine out and had one bar showing on the gauge having covered only 172 miles since fill up!!!Squeezed in 3.65 gals giving around 47 mpg.So that one bar showing means there is still around 3 gals in there!! Hmmph!

Nice knowing that (on mine) I have ~1.5 gal (5-6 litres) of fuel and something more than 60 miles (100 km) available once the gauge starts blinking (with modest throttle management). If it happened at half a tank, I'm pretty sure I would adjust the float or replace the gauge.

Yeah, point taken. Next time the tank has to be disturbed I’ll try it.