OEM Tank Fuel Guage Behavior

[Toymaster]

I have been commuting on my bike last few weeks and have had to pay attention to the fuel, usage and range.  I thought I would leave this info here.  The guage info can be shocking, if not scary, until you learn the idiosyncrasy of the unit.  The capacity indication should be universal, but the MPG is relative to ones bike, mods, and wrist twisting.

 

The important take away is the fuel indicator does not move for the first 22% of the tank, and you have 30% left when the last bar starts to blink.  So, the guage only moves for 48% of the capacity. 

 

Edited May 17 by Toymaster

[Just Footerin]

I would agree, mine's about the same. 

[Hibobb]

Yup, If I fill up when it starts to blink it takes three U.S. gallons.

[CamT]

It’s pretty ridiculous. I eventually got sick of guessing and ran the bike to empty to see how many km’s I got once it started counting back up from zero .

almost 120km driven by the time it ran out . Taking it somewhat easy on slower back roads . 

for a bike that  only gets about 350-380km to a tank , that’s quite a lot I thought 

[Hollybrook]

I keep track of fuel in my GPS - it tells me approximate miles remaining in the tank. 

[random1781]

It's actually kinda hard to electronically gauge fuel level. You don't have a lot of volume, so small variations create big changes in reading, which is even more challenging when you consider that the expected terrain these are in is uneven and creates a lot of sloshiness. You have odd shaped tanks, so vertical distance isn't linear, and to *absolutely* know level, you'd have to have a sensor whose upper and lower limits match the top and bottom of the tank. Not only is that difficult with an odd shaped tank, but it also consumes volume that could be occupied by fuel.

 

This is mainly why there is no accuracy at the top or bottom of the tank. That float's maximum and minimum extents are reached before the top and bottom of the tank. Yamaha plays it safe by giving you a lot of warning at the bottom end because the bike doesn't know how much fuel is left, and similarly it doesn't know how much fuel you put in past it's upper extent.

 

BMW tried to solve this with a resistive strip along the side of the tank that would provide a broader range and more accurate reading, but it was recalled because it couldn't survive in gasoline. It was a pretty expensive part and it failed, so they wound up regressing to the venerable float rather than having the fuel gauge be the most expensive part in the bike.

[Hibobb]

Growing up in the 70's, you just learned to trust the odometer... ahh, the good old days!

[Hammerhead]

This gauge is a rough guide, the trip meter is the god

[Dougie]

I know if I’m getting at least 60mpg, I’ll guarantee 200 miles. I’m only wary when I’ve been riding “on the front foot” and get less. Then I’ll calculate the remaining mileage before I set off home/work etc. 
I love the fuel gauge. It’s a bit “hey, Cyprus no problem, no worries, manana”