Fuelling issue?

Lentarn

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Hi all, been struggling to solve a fuelling issue this last week, hoping someone can help, I’ll put below what’s happened to date (2012 1200gsa)

1. Fuel low, filled up on way to work, on way home, surging, erratic idle, bike cuts out at lights. Restarts after 30s with a bit of throttle and on the 20 min ride home, bike settles down
2. The next few days, no issues then the same happens again, difficult to start , bike surging as soon as I throttle on or decelerate and then catches itself . Lots of bang and pop though
3, started to think bad fuel, so ran tank down. Also checked visually all fuelling connections, cleared breather hoses, checked the tip over valve. Left side breather may have had a restriction as wd40 didn’t flow immediately through
4. Took out for s ride yesterday, all fine, ran tank down to 60 miles. Fuelled up with premium unleaded from no. Set off and weirdly, the fuel gauge is very slow to register the extra fuel. It should have gone to about 150 but by the time I got home it was showing 100 (should have been about 135). Bike running perfectly though
5. Come to this morning, difficult to start and after a couple of miles, bike cuts out completely (dash is on). I coast to a halt, open filler cap, restart engine first time and it runs sweet all the way in

Sparks and coils replaced 6 weeks ago along with air filter. Seems odd it started straight after a full fill up of tank - I was thinking that maybe it’s the last of the crap to go through but this weird fuel gauge issue and the opening of the filler is making me wonder whether it’s something else

Any help really appreciated as ever
 
The filler breather filter comes to mind but you mention you have ensured the breathers are ok. so, it's a puzzle.
 
Try riding the bike with the fuel cap just resting in place over the full distance of your journey instead of firmly shut/locked and see if the symptoms occur
 
Since the issue caused bad starting in the morning, I doubt a vent / vacuum problem. Sounds like bad fuel / water. Not hard to strip off the pumps from tank and to siphon out the whole lot, start from dry..
 
Or buy some Wynns Dryfuel or Silkolene ProFST and chuck that in the fuel tank. :nenau
 
Just ridden home, dropped another bit of fuel in and gauge is now reading properly. No cut outs but seems to be running slightly rough. Very odd since yesterday it was perfect. I’ll check the breathers again and see if keeping the filler open helps as well as the additive.

I guess it’s bad fuel or an intermittent fuel pump issue (with the gauge being off) / guess I check the electrics to the pumps
 
I wonder if that bike has a strip-type fuel contents gauge?

Btw, I think a fuel pump problem would lead to intermittent cutting-out, not rough running.
 
From the internet seems like fuel strips stopped in 2010 and moved to integral with pump. Water or crap in the fuel seems the obvious thing but why the gauge went wonky yesterday has just confused me even more.
 
The fuel strip works on resistance, if water instead of fuel wets it the resistance may well differ enough to upset the reading?
 
I think the 2012 GSA had an electro-mechanical system, to avoid the previous problems, as mentioned in post 8.

Essentially, starting at the beginning again, it sounds like the tank isn't breathing freely. Hence Steptoe's suggestion. I'm not sure what the set up is on the OPs bike, but it's easy enough to consult the parts diagrams to get an understanding, in case there is a charcoal filter in the line somewhere ........
http://www.realoem.com/bmw/enUS/par...2-K255-BMW-R_1200_GS_Adve_10_0470,0480_&mg=16

BTW, I always prefer blowing through the lines with air. Just a high pressure bike pump & tapered adapter will do the job, rather than introducing fluids that could leave sticky residues in the system.

Rough running could be water from ethanol fuels - I get this with bikes only used occasionally, but when in regular use it seems counter intuitive TBH. If suspect best run low & drain entirely, or use one of these emulsifier agents. Seafoam popular in the US, where far higher percentage E fuels are used.
 
Thanks for all the replies so far - hooked up to a gs911 and no codes. Completely removed both breather pipes, flushed through with water and dried and both were clear. Even took the filler out again and cleaned it but its all ok, both vents passing air easily. I'll start running the tank down now and use the open filler if it happens again. It's the fact it's intermittent thats annoying - went out this morning, no issues, running smoothly over 80 miles. Thanks again all, I'll keep ploughing on with trying to trace it
 
Bit of an update - have half filled several times with premium fuel and no recurring issues so far. However, the fuel gauge is all over the place now, seems to get stuck around the 100 mile mark and then eventually goes lower. After a fill up it jumps to say 160 but as soon as I turn the bike off and restart it goes back to between 95 and 105. Looks like I will have to pull the pump out and take a look which will be a first for me. Im now wondering if the tan needs a clean out because of gunk and its covered the strainer and float. Looking at the Haynes manual looks like the tank has to come off - is that right or can the pump be removed with the tank in place enough to inspect?
 
Looks like you have a sticking fuel level float, but that shouldn't affect the engine running.

It might be the fuel pump controller causing the poor running. Make yourself a fuel pump bypass wire ideally switched from an ignition live source but direct from battery will do. Next time it plays up, connect the bypass wire. If the bike behaves OK on the bypass wire that would suggest you have intermittent faults in the pump controller.

It's a pain to connect so not worth running for the long term but a useful test. The search will find how to do it.
 
Just an update on this in case it is of some use to others in the future as I have now fixed it

After the initial symptoms (intermittent) nd having replaced the controller, checked all the breathers, ran a few tanks of high octane duel through and stripping the bike a few times I finally replaced the fuel pump with a second hand one. Seems to have done the trick. I'd found a post on another site where a guy had similar problems - the bike was running but had this erratic fuel cut off and eventually traced it to the main pump being on its last legs - so its power was right on the borderline of pumping enough most of the time with occasional dips into not having enough oomph. Interestingly, I also had problems with the range indicator being all over the place and it seems this might be to do with the pump not being powerful enough to transfer fuel fro the other side of the GSA tank. Anyway, thought I'd write it up in case others are searching in the future like I was.

Should have mentioned - mileage is just under 50k and the guy who had a similar problem was around the same - looks like the pump (in some cases) might start to fail at this point
 
My pump was running low pressure at 42K miles it was down to 2 bar under hard acceleration.
Regarding the range indicator and the computer mpg figures. mine indicated that the mpg was getting a lot worse than it was.
What was happening was the low fuel pressure was causing a lean mixture and in closed loop the lambda sensors were reporting this to the ecu which in turn was increasing the injector pulse width to compensate.
The mpg is worked out by the ecu calculating injector pulse time, engine RPM and road speed, hence reported poor mpg figures.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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