The Bike is Lying to Me

[SuperTed]

Well, not the bike but the distance to empty bit.
Yes I have put a similar thread on before, but that was when I was commuting into central London in feck loads of traffic.
This is different. Filled up and then went off to the bike show at North Weald airfield on May Day, bike stayed in garage for a week and then I went up to the Adventure Bike Shop for a day.
Tramping down the A12 from Chelmsford and I'm coming up to 190 miles on the trip meter. The 'remaining range' is telling me I've got more than enough to get to the next petrol.
So as I'm gently accelerating away from a traffic light about 18 miles later the bike coughs and stops...in the outside lane with a Merc behind me. Coast to the kerb and pump the fuel with the starter for a couple of seconds and it starts up.
Ride down to the next lights where I'm turning off for the petrol station and it stops again. Now not trusting anything I wait for the filter light to go orange before leaning on the start button and having a careful ride round to the petrol. While waiting for a pump to be free it stops again.
Now - the bike had done 209 miles since the last fill up so I am not going to complain about the mpg...BUT having put 14.97 litres in the 16 litre tank the remaining range read-out was telling me I had 41 MILES before empty. I know the 800's are frugal - but they wont do 41 miles a litre!!
The consumption figures actually work out to a gnats whisker under 14 miles per litre (63mpg).
So why is the range read out so wrong?
Any comments welcome...and yes I do know not to leave it so long in future.

 

[smudger64]

I thought the figure you see after the light comes on is the number of miles you've done and not the number you have left? In which case that 41 was how many you'd done since the light came on, not how many you have left?

 

[SuperTed]

Nice thought, Smudger, but I didn't get a light.
I'm pretty sure that there might be something else going on as I have only seen the low fuel light twice in the 5 years I've had the bike.
Unless the bulb has blown...
When first bought I did the 'carry a fuel can and let it run out' trick and when the light came on (this was the second time I'd seen it) I zeroed a trip and carried on. When it stopped, out of petrol, I had done 35 miles and it was still showing 8 miles on the remaining range.
A friend had an F800ST and he had the same problem. Is it something the early bikes had a problem with?
Mine is an 2008 bike and I know there were a few issues with the first ones.

 

[Alan R]

I thought the figure you see after the light comes on is the number of miles you've done and not the number you have left? In which case that 41 was how many you'd done since the light came on, not how many you have left?

what Smudger says above is how it works on my 2013 f800gs.
On a 190 mile run yesterday, ragging the arse off it, fuel light comes on at 168 miles. Accumulative total since fuel light reaches 22, refueled with 15 litres exactly to brim. 56mpg.
Your fuel warning light maybe defective?
Alan R

 

[Magnet]

Early bikes did show a distance to empty when the fuel light came on. It was so unreliable (as the OP has found out) that on later bikes (after 2011?) they changed it so that when the fuel light comes on it starts counting up to show you how far you had travelled since the light came on. I'm not aware of any fix for this issue, I just use the trip and try to fill up at 180 - 200 miles.

 

[snappo]

You've had it 5 years and you're only now realising that you shouldn't trust the 'miles to empty'?

209 miles off a tank and 63 mpg isn't exactly shabby - when I get near to 190/200 I'm already looking for a fuel stop, you can't risk going much beyond 200, as you found out the hard way!

Best tank I ever got was 220, and the worst was 165 - the latter was blasting from the Green Welly, all the way through Glasgow and a fair chunk of the M8, and the former was hooning all over the highlands the week before!

 

[SuperTed]

I haven't trusted the 'miles to empty' for four and a half of those five years, Snappo, but it has been getting more stupidly optimistic in the last year. Like telling me I can do 41 miles on a litre of petrol.
The hire bike I had for our jaunt round France last year was a 2012 Trophy model and that did not have the range countdown; and it never got to the point of having the low fuel light on so I don't know what it did after that.
The bike is coming up for a service within a thousand miles so I will get my tame technician to look at the low fuel light and see if he can get it working again. It would be much more use to me than anything else.
What I was doing when commuting in to central London was to have the 'range to empty' on the screen until it got below 100 miles and then switch to trip 1, which generally had about 150-160 on it at that point, and fill up by 180.
But I stopped commuting in July and have been retired since January, and it hasn't been an issue until it caught me out the other day - hence the thread.

 

[Bem]

Ah, then stop being retired and get commuting again - simples!

 

[JJH]

I've read your post twice and unless I'm reading it wrong you put just under 15 litres in from empty. BMW state 16 litres but if you run out you will get over 17 in. I wonder if theres somthing else going on. JJH

 

[v8legend]

I've read your post twice and unless I'm reading it wrong you put just under 15 litres in from empty. BMW state 16 litres but if you run out you will get over 17 in. I wonder if theres somthing else going on. JJH

That was my thoughts. I've run my bike down to no miles left with no issues, and got 16.45 litres in.

 

[SuperTed]

Having not looked at this for a while I read JJH's and v8legend's comments with a certain amount of agreement.
I am pretty sure that there is an issue that is more than just the low fuel light not working.
Unfortunately, for me, my tame technician is off to Germany next week for the launch of the new 310 (it must be such a terrible thing to have to do, all expenses paid trip to ride a few new bikes...who would want to do that for work?) so it looks like the end of the month before mine gets looked at.
I am still riding it mind.
Off down to the BMF Merlins & Motorbikes show at Headcorn on Saturday with the guys'n'girls from the Fellowship of Christian Motorcyclists; if you're there stop and say Hi; and then back up to the Adventure Bike Shop next weekend.
Its getting filled up more often for the moment though.
Once its been looked at I'll let you know what he finds.
SuperTed

 

[SuperTed]

Update

Well my tame technician got back from his jaunt to Berlin to ride the 2017 bikes (it must be a terrible thing having to take an all expenses paid trip to an interesting place and have to ride a fleet of new bikes when you get there, I just don't know how he copes with it all) he collected the F8GS on Saturday and he now tells me that the gubbins in the tank; float assembly, float, and electronic sender; need replacing. This is why I haven't been getting the low fuel light.
He has measured the tank volume and it is at just on 16 litres. Since BMW say the capacity is MAX 16, and not all of it is usable, the 14.97 I put in when having the problem seems about right. He is bringing the bike back to me this Saturday and the first thing I'm going to need to do is fill it up. After that we will see when the low fuel light comes on and how much I put in at that point. Hopefully not part way down the A12 between Chelmsford & Romford as there isn't any petrol on that stretch. I'll keep you posted.

 

[alex_rsa]

I can regularly get 16.5 litres in....fill the bike on the side stand it will take a bit more then on the centre-stand.

My commute is 200 miles a week so I always ride until the mileage countdown is nearly into single figures. Been caught out once when the bike was new to me.


I would not trust the mileage countdown in riding conditions I am not familiar with as it is a guestimate. When I had a fuel pressure (over-fuelling) problem the bike would be empty with 40 miles to go.

 

[SuperTed]

I Have Seen The Light!!

The low fuel warning light that is.
I was starting to wonder just when it was likely to come on and it finally did tonight on the way home.
So, got the bike back on Saturday evening as promised and it has now got all new bits in the fuel tank. The float, float rail, contact strip, sender, and a couple washers have all been replaced. The rail was quite worn towards the bottom of its run and my tech reckons that the float was sticking at some point and never getting far enough down to turn the low fuel light on.
When he picked it up it had no light on, two bars on the gauge and about 60 miles on the range to empty.
When I got it back the light was on, there were no bars on the gauge and the range to empty said: ---
So that was encouraging.
Filled up on Monday and headed up to the Adventure Bike Shop for Tuesday & today. So a roughly 100 mile round trip yesterday and then up to Sudbury today and I'm hoping for the light to come on on the way home tonight. Which it did with 186 miles on the trip meter. Filled up 5 miles later with 13.8 litres. So it comes on when there's about 2.5 to 3 litres remaining.
Didn't notice what was on the range to empty but it works out that I had about 30 miles to dry.
So that's fair enough, I can work with that.
I'll talk to you all again next time I have a problem, or something to share.
SuperTed