Another random fuel gauge (float type) thread

[siwilson]

I looked through the other threads on this topic but none are quite what I have experienced.
Mine's a 2008 R1200GS and when I bought it it had the ribbon type gauge. Rather then purchase another ribbon I decided to do the modification to float - swapping the wires and reprogramming the ECU etc.
My (used) float mounts on the filler tube.
I've disassembled/reassembled it all multiple times trying to get it to work reliably. I thought I'd got it. I set off on a trip with the gauge showing around 3/4 full. After a 100 miles or so I was beginning to feel quite impressed that it seemed to be sipping fuel. Of course a few miles later the engine stopped, no fuel. Had a little fuel left in a can so carried on to the next garage and filled up. The gauge seemed to be reading normally and when it got down to two bars I filled up again, except, it was nowhere near empty and only took a few litres. But, now the gauge only reads a couple of bars with the tank full.

I've run out of ideas as to what could cause the gauge both to report both more than, and then less than, the amount of fuel present.
I guess I'm going to have to take it all apart again, but, before I do, anyone got any idea what could be causing this?

 

[dub 24]

My 2012 GS has the float from new. It does something similar to yours. When I fill up it shows a full tank and progressively reduces as I drive. when it gets to the low fuel point the light comes on as it should. When I fill up I can only get 11 to 12 litres in meaning I'm getting the low fuel light at 8 to 9 litres as opposed to the correct reading of 4 litres. I'd be interested to see what you find when you have figured it out

 

[Santa-2512]

My 2012 GS has the float from new. It does something similar to yours. When I fill up it shows a full tank and progressively reduces as I drive. when it gets to the low fuel point the light comes on as it should. When I fill up I can only get 11 to 12 litres in meaning I'm getting the low fuel light at 8 to 9 litres as opposed to the correct reading of 4 litres. I'd be interested to see what you find when you have figured it out

Hmm something dosent sound right

How much do you put in to fill the bike from empty ?

At what miles (range) on the kombi, does the low fuel warning light come on..

How much exactly are you putting in ?

How many miles range do you get shown once the tank is filled ?

 

[siwilson]

I've found some good extra clues here as to what may be going on. Haven't had time to investigate further yet.

https://www.r1200gs.info/threads/conversion-from-fuel-strip-sensor-to-float-without-converter-box-as-permanent-fix-oil-cooled-bikes.53781/unread

 

[dub 24]

Hmm something dosent sound right

How much do you put in to fill the bike from empty ?

At what miles (range) on the kombi, does the low fuel warning light come on..

How much exactly are you putting in ?

How many miles range do you get shown once the tank is filled ?

Hey Santa I can't answer any of those questions with definite answers. I fill the bike till I can see fuel in the neck. I drive to work and usually get up and down to work 2 1/2 times (145 miles )before the low fuel light comes on. When I fill up the bike then it takes 11 to 12 litres. The fuel gauge always show full as well. Sorry to be so vague

 

[Santa-2512]

Hey Santa I can't answer any of those questions with definite answers. I fill the bike till I can see fuel in the neck. I drive to work and usually get up and down to work 2 1/2 times (145 miles )before the low fuel light comes on. When I fill up the bike then it takes 11 to 12 litres. The fuel gauge always show full as well. Sorry to be so vague

I think your figures are slightly off

The bike holds 20L with a reserve set at 4L both approx btw

in old school money that would be 4.39gallons

so 20L = 4.39 G - 4L(res) =0.87 G = 3.52G before reserve

Like you, I fill into the filer neck, & refill when the low fuel warning comes on (anywhere from 35-48) miles remaining

Looking at my last fuel receipt from last Tuesday

So reserve light on , so 4L left in tank Range varies from 158m- 171m

It took 15.63 litres to fill @1.549 = £24. 21

so give or take 15.63L + 4L = 19.63L so 0.37L discrepancy approx.

I'd say your putting in more than you think.

 

[dub 24]

Cheers Santa. Just thinking about it. My reserve light comes on with roughly 65 to 72 kms showing in old money that's 40 to 45 miles left. I also have the thick bottom bar plus two thinner bars showing on the fuel gauge if that makes sense. Is that what shows up on your gauge

 

[Santa-2512]

Cheers Santa. Just thinking about it. My reserve light comes on with roughly 65 to 72 kms showing in old money that's 40 to 45 miles left. I also have the thick bottom bar plus two thinner bars showing on the fuel gauge if that makes sense. Is that what shows up on your gauge

ive got a 2011 so effectively the same

TBH i never really pay much attention to the gauge,, I think its the thick bar thats left when it shows fuel and the range is sub 50 miles

I know that when it gets to below 50 miles range its time to fill

I think 10 miles range was the lowest ive ever had showing eek!

Mind you, have you spotted the glaring error in the handbook showing the fuel gauge

 

[TLSgazza]

On my 06 adventure, if I have the fuel hose in the tank until it shuts off, I can then pull the filler out and usually fit about 3-4 more litres in. Last Sunday I filled it up like this and with 35 miles still showing on my range (I'd ridden 375 miles on this tankful) I fitted in 34.3 litres. The official capacity is supposed to be 33 litres but I have put in excess of 36 litres on many occasions.

 

[siwilson]

I think I've found the problem and fixed it. When I converted it from strip to float, I had difficulty in de-pinning the connector to the ZFE. Because I didn't correctly follow the instructions I partially mullered the pins.

I tried and failed to find some replacement pins but then realised I could use the spare two from the strip, as they are not needed. I was much more careful de-pinning these two and they came out without any problems.

I connected it all up but still it didn't seem to work - the gauge in the display stayed at the same reading no matter what position I put the float in. I decided to put it all back together anyway, then went for a ride to the garage with just one bar showing. Filled up, and as I rode back the gauge slowly rose to full. Must be some strange software smoothing on the gauge that depends on motion. More than just running the engine as I'd already tried that.

 

[siwilson]

I finally got it all working. The last piece of the puzzle was the float was getting tangled up on its on wiring. A quick fiddle with the wires and extra care when re-fitting the filler cap and all seems to be working well, finally. I lost count of how many times I had all the plastic and the fuel tank off.