BMW F800 Forum banner

Engine cuts out

2K views 14 replies 9 participants last post by  jrwooden 
#1 ·
Hi all. Here’s my first post and thanks for taking a look.
I was returning from some backroads and trails today and was running down a major hwy when the engine just cut right off.
I pulled onto the shoulder and it kicked in so I pulled back onto the hwy.
it did this the last 30 minutes of my ride and I was vsry grateful to make it home.
Ideas? Thanks!
 
#3 ·
Welcome to the forum, Bill. The first thing I would look for is a loose connection at the battery.
 
#4 ·
Interestingly it cuts out for 2 seconds then runs for about 8 seconds. If I don’t move the throttle it just repeats and feels like it bump starts each time.
If I roll off the throttle the engine shuts down, not great on the hwy, and it fires back up with the Start button
 
#10 ·
This is a long shot, but my 2009 F800 was surging and cutting out like it was having fueling issues while I was on an off road trip, and it turns out the cutoff switch for the kickstand had been damaged. The cutting out of the engine got worse and worse until it was unrideable. We ended up having to bypass the switch in order to keep the bike running. You might check that the switch didn't take a hit while you were riding. Best of luck getting it sorted. Ben
 
#11 ·
Do you have a Motoscan or a GS-911? I would start there because this feels more like an electrical issue to me. Especially since you said it idles fine, the idle hoses don't seem to be the cause.
Since you said it happens only when you coast i.e. close off the throttle while in gear, I'm wondering if there's some sort of vacuum issue that's causing fuel flow problems. I remember reading some threads about similar issues due to the charcoal canister getting saturated, but this is a wild guess on my part, and I myself can't really explain what I mean exactly.
I had an engine cut-off issue on mine a while ago, but once it cut out, it wouldn't fire back up until I cycled the ignition (turn off, wait a few seconds, turn back on). The issue was the fuel pump, which apparently does wear out due to the tank design and starts seizing, thereby tripping the electronic fuse.
I spent a couple of months checking/swapping various parts when a fault-code scan could have revealed the problem instantly.
 
#12 ·
I recently had something similar. Turned out to be the right switch cluster had a connectivity issue. Any time I wiggled the cabling in to it either killed the ignition or enabled it. I took the cluster apart, cleaned and re-seated the connectors and reassembled. No problem since. Quickest way to see if its remotely similar is wiggle the cabling while the engine is idling and see if it cuts out.
 
#13 ·
Just to reconfirm: This is about an F800GS? Because this seems to be the F850GS forum. These are completely different engines.
In case it is an F800:
The charcoal filter saturation is easy to check, just unplug it from the airbox, then ride in the rain. The specific mechanism for this was as follows: The charcoal filter is supposed to be between airbox and fuel tank breather hose. During rain, the bike sucks a lot of rain in to the airbox (this is normal and a-okay), where it will flow in to the charcoal filter and saturate it, causing it to clog completely(this is not normal and not intended). The fuel pump is then unable to pump fuel from the tank because it has to suck against a vacuum - leading to a fuel starved engine dying. This only happens on the GS and GSA, as the other F800s have a differnent airbox design and the charcoal filter opening is located elsewhere on those bikes. The solution is a T-shaped junction and another breather hose going down between engine and swingarm pivot.

So the question here is: Was it raining when you were riding? If it wasn't, it wasn't the charcoal filter.
Cutting out when setting throttle to idle is a regular problem for the S and ST crowd. The list of possble culprits: Dirty idle stepper valve, broken idle stepper motor, old idle setting hoses that collapse under heat and suction, broken throttle body potentiometer, cracked throttle to head rubber gaskets, possibly ( unconfirmed!!) deteriorated lambda sensor.
 
#15 ·
My go-to for checking for charcoal canister issues it to hold a sheet of paper very close to the gas cap, then pop it open with the key and see if it vents presssure,
or releases a vacuum ... it's sometimes hard to tell the difference ... so that's what the paper is for... if you vacuum either canister or perhaps the checkvalve at back of see could be the issue ... also once you pop the cap the bike will run fine for a while as the fuel pump is no longer working "against" the vacuum.

I 2nd the motions on low fuel level (can cause fuel pump to overheat), bad battery connections.
When you pull the faux-tank to check the battery connectdions after checking ... put voltmeter on battery ...
when running you should be at 13.X volts.... low system voltage can cause weird crap (bad stator, bad regulator, bad battery..)

Other light reading here:

Start here http://www.advrider.com/forums/showthread.php?t=1064820

http://www.advrider.com/forums/showthread.php?t=599568

and then go to the http://www.advrider.com/forums/showthread.php?t=415604
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top