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Damn fuel gauge inconsistency


Spitfire

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I drove 73km ( = 45.3mi) with "flash E" till the engine starts stuttering. Tested it one time.

If you turn on ignition the dash needs some time to calculate an accurate value. You must imagine the reedings from the sensor fluctuating a lot so you need lets say 200 readings to show something what is close to reality. But people would get nervous if the dash not shows the fuel gauge immediately...so it shows you "something" in the beginning. :)
 

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I found these posts I made some time ago when this topic heavily interested me:

 

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Today, my engine began missing after a little less than 360 km. I was certain there should be at least one litre left of fuel. The stuttering became worse, and I still had a bit to go to the gas station. In the end, I began shaking the bike from side to side, which helped momentarily. We did make it to the petrol station with 365 km showing, 70.9 km since the "E" began flashing. When the fuel sat above the filler neck I had 12.9 litre on the pump, meaning there should have been 1.1 litre left in the tank. Perhaps there was. Perhaps not. Anyway, it means that there is 10 % less capacity than promised until sputtering. Pretty annoying.

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I am now pretty confident that Yamaha has tried to make a "smart" fuel gauge. Instead of giving fixed number of litres remaining, the bike tries to guesstimate the remaining number of km or miles before empty. Unfortunately, it doesn't seem to to this based upon the actual consumption since the last refueling, but on some kind of average over time. This is then why we find ourselves with different amounts to fill up after the E(mpty) starts flashing. It's either that, or the gauge/sensor is highly inaccurate.
 
On my bike, for the first 4 times, the E began flashing after 233 km, but the amount of fuel I could get in varied by 20 %. The higher the consumption displayed by the on board computer, the more fuel I had to put in.
 
Then, today something strange happened. My display was down to the final block with 205 km since last reset. However, after about 15 km, I got another block showing up on the display, as if more fuel had been added. In the end, the E began flashing after 256 km. I rode for another 59 km and filled it to the brim with 11.43 litres for an average of 3.6 l / 100 km. Or 65 mpgUS. 
 
Hopefully, the thing will continue to increase in accuracy as time goes by. Ideally, in my world, the 7 segments (6 bars plus flashing E) should have been equally split in 2 litre segments. That way, you would know that when the final bar only was showing, you had 4 litres left. When the E began flashing, you had 2 litres before empty. That way it would be very easy to calculate how far until empty, and you could also slow down to stretch that a bit if required. 
 
As it is, which is overly pessimistic, all the tank gauge does it make me worried I'm about to run dry 130 km (80 mi) before I actually would. Way too much warning.

 

 

Whole thread with plenty info from several members can be found here 

 

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So my fuel gauge saga continues.

Fill the tank to the brim from 2 bars with 2.5 gals. 225 miles to go. Flat desert, 90f heat. Bombing along at 80-85 mph, getting around 40-45 mpg, eating up highway, life is good. But....

Down to my last bar, can I make the next gas station out in the desolate desert?

Stop at the rest stop to partake in the wet t-shirt contest, think I acquitted myself quite well. Lol.

Next gas station is 25 miles and of course upon start up, the dreaded E flash. What happened to my full bar Yamaha?

Can I make it to the next station 25 miles away? Against a 20-25 mph headwind? Or will I end up pushing or thumbing for gas?

What say you?

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  • Global Moderator

25 miles should be easy enough.  I have done that with the flashing E many times and have yet to run dry. 

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  • Premium Member

Once you're on flashing E you might want to drop your speed down to a more ECO 65-75MPH if you're trying to stretch it.

DewMan
 
Just shut up and ride.

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From the point E starts flashing, 25 miles should be safe unless you go flat out, but just to be sure it wouldn't hurt to reduce speed a bit, as recommended above.

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firstyammerha

I don't think I've put more than 3.2 gallons in mine after riding 30 odd miles into the reserve. I fill up to the owners manual max fill spot and have 50 odd mpg average showing on the dash. Therefore I figure for me that 40 something miles is a safe range for the reserve. The ECO message is a permanent fixture on my display. This fuel gauge doesn't compare to my last two cars for accuracy.

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Phew, made it the 25 miles, going 60-65mph. Stuck on the side of the road would have sucked.

Filled up with 3.2 gallons but like to the brim max.

So how much was left in the tank if I could put in 3.2 gallons?

For touring, when you may not know when or where the next gas station will be, important to KNOW how much is in the tank. Miles per tank helps but like isn't that the point of a fuel gauge?

And this full last single bar turns into only flashing E when you stop and restart it just drives me bonkers. How much gas is really left for how far can I go?

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My bike had been missing for several miles and barely running when I reached the fuel station, and I still only managed to get 3.41 USgal into the tank. That was with waiting for the level to set several times, trying to get as many drops as possible inside. There is no way there was more than a quarter gallon of free space in that tank, meaning the pick-up possibly isn't always sitting at the bottom of the tank, reducing factual volume. Or something else than actual fuel starvation is causing the missing; my Volvo would stutter depending on the computer reading to warn that fuel was low, even if there was plenty left.

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FWIW, the fuel pickup from the tank appears to be on the bottom right hand side.

Could gain a bar when I tilt the bike to the right at start up.

The tank is tilted down from front to back.

So when you are low on gas, ride a wheelie leaned over to the right to get every last drop.😋

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  • 1 month later...

So I am out and about exploring on the Spitfire. 40 miles, Twisties, 2500 ft elevation drop. In my mind, am Guy Martin running the isle of Mann, attacking the corners but with survival a main goal as well. Realistic 40-50mph.

 

Start with 4 bars.

Get to town, putter around. Start back up and it's flashing 1 bar. There is no way that I used half a tank in 40 miles going downhill.

Just for fun, tilt the bike to the right twice. No change, still flashing 1 bar. Shut off the bike and restart. Bam, magically back up to two bars. Drive a couple miles and quickly drops to one bar but not flashing. 

Damn fuel gauge inconsistency!

Can't believe that no one else has the same issues.

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