Help! My bike is suddenly cutting off.

vaclove

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This morning, I got to France to begin a 3500 miles round trip over France, Alps and Pyrenees. And guess what? My bike was running faultlessly for 15000 miles and now it suddenly started to suddenly lose power. Sometimes engine just cuts off. Happened to me more than 10 times at various occations. Sometimes at 70 mph on motorway, sometimes at traffic lights.

I have noticed, the problem happens when my tank is getting empty. When I refuel, bike goes smoothly until some tank gets emptier again. Almost as there would be some problem with the fuel supply. Anyone has experience with this?

I am getting concerned about the bike and would appreciate any advice/opinion what would be best think to do.
Should I call the BMW breakdown? Or try to find a dealer to fix it?

This is not very encouraging beginning of the big trip but hopefully things get better.
 
Try a higher octane fuel. The stuff in the blue pumps is 98, the green ones 95. I found my 1150 ran better in France on the higher octane stuff
 
I don't think the F800 has a fuel filter, I have looked in the workshop manual and checked the maintenance schedule and found no reference to one.

Dose the bike start first time after cutting out?

Is the fuel tank vent line blocked or trapped, this is a known problem which will cause erratic running. Next time it stops place your ear close to the filler and open it quickly, if you hear a sucking noise you have a blocked breather.
 
Sooty09 said:
Does the bike start first time after cutting out?

Is the fuel tank vent line blocked or trapped, this is a known problem which will cause erratic running. Next time it stops place your ear close to the filler and open it quickly, if you hear a sucking noise you have a blocked breather.
Click to expand...

+1 :thumb2

Or possible fuel pump/filter
 
Last edited:
The fuel tank vent is under the trim panel behind the filler cap. It is designed to shut off the flow of fuel if the bike tips over. Follow the vent line down to its low point near the swing arm pivot. With the filler cap open you should be able to easily blow up the vent tube in to the tank.

msut01


Ventvalve.jpg


Back to the filter comment, yes a basic strainer mesh is fitted to the pump to prevent large bits getting into the mechanism, this has no cleaning schedule or any suggestion of replacing it in the service notes.

Fuelpump.png



Its item 5 above, has anybody had to clean a strainer yet? Is the canister between item 5 and the pump body 1 a finer filter integrated with the pump?
If so its a very expensive thing to replace.
 
Hello.

I was under the impression that if the 800 was run on lower/higher octane fuel, the bike was designed to cope with this. Or have I misunderstood?
 
Thanks to all

Thank you all for very helpfull comments. I did not have internet access past few days. We were trapped in unbelievable storm when going from Reims to Colmar, but then got amazing weather in Black forrest...
Anyway, during the rain and cold weather the bike worked fine, but felt bit weak. I kept topping up fuel, just in case...
I have stopped by BMW dealer in Germany and let them check the bike and this is what they came up with:
The engine was switching off, because it was overheating to prevent damage to the engine. This was cause by the fan failing to start, because there was something trapped in it (dont ask me what or how).
This sounded strange to me, ask the temp. of coolant was normal. Their diagnosis would fit to the fact that it was 30C when it started and that I drove slowly. Maybe, the topping up fuel was not as relevant, because at the same time, I stopped, so the engine could cool down a bit?? Noting happened during the cold weather and storm.
Anyway, that is what computer said, so they reseted it and bike now runs as new :thumb2
Thanks again to all for your comments and valuable advices.
 
vaclove said:
I have stopped by BMW dealer in Germany and let them check the bike and this is what they came up with:
The engine was switching off, because it was overheating to prevent damage to the engine. This was cause by the fan failing to start, because there was something trapped in it (dont ask me what or how).
This sounded strange to me, ask the temp. of coolant was normal. Their diagnosis would fit to the fact that it was 30C when it started and that I drove slowly.
Click to expand...

This is a well known issue (although I can't find the thread) often caused by a build up of mud etc. I always pay particular attention to the fan/rad when cleaning my bike.:rob

It's interesting that your temp guage didn't rise at all. Neither did mine when my top hose came off.:confused:

Let's hope your trip continues without any problems.:thumb
 
This sounds like a fuel pump problem. Check the symptoms aginst the problem I had http://www.advrider.com/forums/showthread.php?t=599568 and if the behaviour is the same it's almost certainly the pump.

The fan problem shows up first with the oil warning light coming on. I've seen this on several 800's where the oil light has come on but I've never heard of the engine cutting out because of it.
 
Thanks Murdoch

Thanks Murdoch for the link. Those are very valuable information. After the dealer "fixed" the problem with the fan, the engine run faultlessly for more than 2000 miles. In some cases in up to 30C and also with tank getting pretty empty.
As you describe your issue, it was pretty much the same in my case.
The dealer claimed, the pump is ok, but I will definetely keep in mind that this might be the real issue when the symptoms should reoccur.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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