TROUBLESHOOT: 2011 BMW F800GS engine cuts out
Posted: 13 Jan 2018 10:41
In the middle of BFE along the UTBDR, my F800GS started cutting out intermittently. I quickly surmised it was the kickstand switch. One reason this came to mind so quickly is that the guy riding the F800GS in the UTBDR teaser movie had his kickstand switch do the same thing!
I removed the kickstand switch. Problem solved. OMG!
Troy, don't you realize the risk of your kickstand switch being down with the transmission engaged?!!! How can you be so careless with your life and of everyone around you?!!! Yes. Yes I do.
So about a year later, on my last big bike 3 day adventure, my F800GS developed a mystery issue where it would just start dying while I'm riding--just cut out and die. Sometimes it would fire back up before I rolled to a stop. Other times it would strand me for 5 minutes before it would start again. Not the kickstand switch this time. This is different.
I started to notice these patterns:
On my way home and before my final gas stop of the 3 day trip, I had formulated a theory that my gas tank is not breathing. It is my understanding that gas tanks have to be able to pull in air to displace the fuel being sucked out of the tank. Otherwise, a vacuum is created. A strong enough vacuum would compete with the fuel pump's power to suck fuel out of the tank. The more fuel that is pulled out of the tank, the greater the vacuum, and thus, more likely the bike will be starved of fuel.
When I did get to the gas station--after being forced into a huge ditch to get my now coasting motorcycle out of the way of 65MPH traffic, I noticed that when I opened the gas cap, there was a significant whoosh of air rushing into the tank. Theory confirmed? Me thinks so.
I did not have enough miles left to test the theory further, but if my theory is correct, I should be able to put the issue off for many miles by simply stopping to open the gas cap to eliminate the vacuum.....or even ride with the gas cap popped open. Yes, I understand I do not want dirt to get into the gas tank.
You might say this problem really sucks. Get it?! It's a vacuum reference. You know, because of the suction caused by the vacuum? Never mind.
On older vehicles, I've seen this vacuum problem fixed by simply buying a new gas cap--as the breathing hole is in the cap, which has become clogged. On my F8, the gas cap is a more permanent structure than a simple twist-off cap, and it is keyed to the bike's ignition key.
One of these days, I'll not be too lazy to actually look into a resolution. Hopefully I do that before my next big bike adventure...which may be in TX or Canada. Haven't figured that one out yet.
I removed the kickstand switch. Problem solved. OMG!
Troy, don't you realize the risk of your kickstand switch being down with the transmission engaged?!!! How can you be so careless with your life and of everyone around you?!!! Yes. Yes I do.So about a year later, on my last big bike 3 day adventure, my F800GS developed a mystery issue where it would just start dying while I'm riding--just cut out and die. Sometimes it would fire back up before I rolled to a stop. Other times it would strand me for 5 minutes before it would start again. Not the kickstand switch this time. This is different.
I started to notice these patterns:
- I can start the day riding and ride for hours before the problem starts
- Once the problem starts, it continues to happen often--as in every 1/2 mile to 3 miles or so
- The problem goes away after I stop to fill the tank (AHA!)
On my way home and before my final gas stop of the 3 day trip, I had formulated a theory that my gas tank is not breathing. It is my understanding that gas tanks have to be able to pull in air to displace the fuel being sucked out of the tank. Otherwise, a vacuum is created. A strong enough vacuum would compete with the fuel pump's power to suck fuel out of the tank. The more fuel that is pulled out of the tank, the greater the vacuum, and thus, more likely the bike will be starved of fuel.
When I did get to the gas station--after being forced into a huge ditch to get my now coasting motorcycle out of the way of 65MPH traffic, I noticed that when I opened the gas cap, there was a significant whoosh of air rushing into the tank. Theory confirmed? Me thinks so.
I did not have enough miles left to test the theory further, but if my theory is correct, I should be able to put the issue off for many miles by simply stopping to open the gas cap to eliminate the vacuum.....or even ride with the gas cap popped open. Yes, I understand I do not want dirt to get into the gas tank.
You might say this problem really sucks. Get it?! It's a vacuum reference. You know, because of the suction caused by the vacuum? Never mind.
On older vehicles, I've seen this vacuum problem fixed by simply buying a new gas cap--as the breathing hole is in the cap, which has become clogged. On my F8, the gas cap is a more permanent structure than a simple twist-off cap, and it is keyed to the bike's ignition key.
One of these days, I'll not be too lazy to actually look into a resolution. Hopefully I do that before my next big bike adventure...which may be in TX or Canada. Haven't figured that one out yet.
