I've been on to a friend who's a consultant engineer on automotive side. Given the symptoms (OK with open throttle, problems with partial throttle), he reckons it's nothing to do with air or fuel filters, nor with blocked injectors, and that it's likely to be something to do with engine management.

We discussed the O2 sensor likelihood and he concurs that under fully open throttle the sensor is ignored. He's concerned that if the sensor is detached the system might go into a 'limp home' mode with substantially reduced power. Mind you, given your bike's current state, that might be an improvement.

I'll do some more digging and see what I can find.

Tim

__________________
"For sheer delight there is nothing like altitude; it gives one the thrill of adventure
and enlarges the world in which you live," Irving Mather (1892-1966)

If you can get a multimeter it's possible to meassure the signal from the O2-sensor, it should be very low when engine not running and increase to at least 0.4V when the engine has idled for a while.
Even in Khartoum it should be possible to get an O2-sensor it doesn't have to be the original. There is (or was) a BMW-dealer close to the Sailing club and I guess there should be other dealers around.

But as Tim says try to disconnect it and see what happens. Is there a way to reset the ECU or TPS-signals?

It might be smart to fix the sidestand-issue before you start messing with the O2-sensor.

Edit:
Some more info: Bosch lambda sensor - Checking and trouble-shooting

I would re-boot the firmware before doing anything else, esp given the preceding advice this is likely to be an engine management problem.

Hi Docsherlock,

How do one reboot the firmware ? I am having similar stalling issues which started a few weeks ago, went away, but came back again today. Took of my side stand last night, cleaned the side stand switch with some WD40 and this morning it seemed fine, although it was only an 8 mile commute into work.

We are also leaving London towards Cape Town down the East Coast in September this year and I think I will now invest in a GS-911 and get to grips with it before we leave and also take it along on the trip.

dajg, I am interested to see how you get on and if you find a fix ... I will be following this thread closely ...

__________________
--
London to Cape Town 2010 - http://bit.ly/uk2za

ok...

so i disconnected the throttle positioning sensor. the bike still runs, and the stalling issue is the same however the engine warning and the general warning lights came on.

i tracked down a bottle of octane booster!! ok so on the other side of the street 60 west giraf from the kenyan embassy go south 500m look for "my car" shop they have a bunch of stuff.

however, i added the octane booster but no improvement.

i'll try some chain lube or wd40 on the side stand switch but i don't think this is the problem.

once the bike is hot i can replicate the problem on the centre stand at camp. i pulled the seat off and listened to the fuel pump. sounds good, and runs for 1-1.5 seconds AFTER the engine dies so i think pump is ok.

i haven't managed to figure where the lambda sensor is (or what it looks like...). i will disconnect it (stuttgart reckon i can ride without it) likewise the engine temperature guage (when i find that too... the tech DVD is really rubbish for diagnostics or locating parts).

i'll give the battery a try.

can anyone explain to me how the fuel pump starts? after stall, it takes 3-5 seconds for the engine to catch when i hit the starter button. sometimes i have to turn the ignition off, wait a few seconds, on then hit the start and its back to 1-3 seconds before it catches. i thought maybe if the fuel pump was cutting out (though as per above seems unlikely - maybe fuel pressure sensor fault...?) and the engine was starving, then taking a few seconds longer to start than it would after a normal shutdown due to time taken for the pump to send fuel to the injectors.

is it possible that it IS fuel pump after all? that the bike warms up, then the fuel pump warms up and begins to fail? i keep ruling out fuel pump because of the total loss of power i.e. engine failure. its not gradual, and the bike does not drop to idle - just dies.

anyway, i'll keep chipping away. still got 2 weeks left on the visa...

thanks guys
dave

Number 5:

This was posted on Advrider & F800Riders about rebooting the computer:

they suggested resetting computer by holding positive & negative battery cables together,

"Don't know if it matters or not but the way i have been instructed to do this is to leave the positive cable connected to the battery then short the negative cable to the positive cable/battery terminal for approximately 10 minutes."

"Here is a wild guess, after having problems and refusing to start for some time, the bike reboots itself. Anyone with an iPod is likely familiar with this. If the bike rebooted itself, this would also explain bad fuel economy for the next 100 to 500 miles, depending on riding style and conditions.

As I said before, my bike did this and disconnecting a battery cable and shorting it to the other battery cable allowed the bike to start right up. 1,200 miles since and no problems, other then slightly off fuel economy for the next few miles (few because I drove it through a ride cycle)

If someone has this problem, give a reboot a shot, nothing to loose, just make sure all wires are disconnected from one battery terminal and then short them to the other battery terminal that still has wires connected to it. Do make sure one battery terminal has absolutely NO wires touching it, and this is 100% safe.

This is the official BMW method of rebooting the onboard computers, though normally the techs at the dealer do it."

I think you are wise to take a GS911 and netbook/bluetooth phone and a BMW service manual; I believe Haynes are publishing a manual in the Autumn. I also wonder whether you should take a spare side stand switch, some spare fuel injectors a master chain link and riveting tool, lambda sensor and fuel pump controller, perhaps off a crashed bike? depends on the cost I guess, but these seem to be the bits causing trouble though one gets a skewed view on the internet of just how common this stuff actually is. I would take the tool, manual and chain spares and make sure I had a good logistical chain in place for spares to be fed-exed out should I need them - at least you can diagnose the problem with the GS911 and netbook/phone.....

I'd also consider taking a spare battery kept topped up by a solar charger and stick it in the top-box - but then I am a bit paranoid......

Ride safe,

Sherlock

Also have a look at this thread on Advrider

My F800gs STALLS LIKE ITS RUNNING OUT OF GAS! PLEASE HELP!! - ADVrider

I think the computer re-booting is described in there somewhere by Joel Wisman who is a very helpful BMW tech - you could probably email him and ask him about it - he's a top bloke on the forum.

Hope that helps,

Sherlock

Cool, thanks guys. I have found that post on ADV, thanks. I am going to try and reset my computer tonight when I get home as I don't want to do it at work and then mess something up so I can't get home

I also suspect fuel pump on mine actually ... I see a new fuel pump assembly is around £280, so will have to get that replaced under warranty. I just went down and looked at the fuel pump under the seat and wires are loose that should be fastened with cable ties. Suspect this was removed and/or worked on during my latest engine rebuilt around 14.5k miles. I also noticed some white residue on the fuel pump electronics ... not sure why ???

Sherlock .. yeah that is a lot of spares, not sure we will be taking so much with us It's funny as mine first cut out a few weeks ago after leaving my bike on a slight incline with little fuel in it ... I managed to get to a petrol station and filled up all the way taking only about 11litres, so there was at least 4-5 litres in the tank. I thought because of the incline and low fuel, it might have sucked some air ? After filling up nothing running fine for weeks until 2 days ago when it didn't wanna start first time .. had to slightly give it some throttle while cranking ... yesterday was even worse.

Engine completely died while riding .. about 10 times. Sometimes it starts back up immediately, sometimes it doesn't. Stopped and waited for a while with the bike on the centre stand, started back up and rode home with no problems although slightly nervous in the fast lane of a motorway

Keep us updated on your progress dajg !!

__________________
--
London to Cape Town 2010 - http://bit.ly/uk2za

mogoose...

does your bike go ok for 20-50km before it dies the first time, then you restart and it dies 10 times again in the next 20km...?

does it die those 10 times (after the first occurance that day) when you back off the throttle...? (i don't mean back to idle, i mean say from 4000 revs to 3000 etc).

because that is my problem.

what changes after 20-30km? is the fuel pump hot or something? the bike would reach normal operating temp after a couple of k's.

the first 20-30k's i do here on a test ride after fiddling with something, i do in heavy traffic - lots of gear changes, fan can be on, and obviously i hammer the throttle to try get it to fail (which it does eventually...)

then after the first failure, i get failure every time i back off the throttle. i can shift right up to 6th and 120kmh but then as i slow down it goes on me.

i try keep the throttle in the same position and just use the clutch & gear down but i struggle with using the front brake while i am holding the throttle...

thanks
d

Almost exactly .. started fine, heavy traffic, probably after only 10km .. sometimes hard acceleration to get out of traffic, etc ... and then it just died. After that it did it all the time until I left it for a while and then started back up and was fine for probably another 10-20km to get home.

This morning started first time .. all the way to work, although slightly lower temperature, no problems. Did that side kick switch clean after reading about Tims trouble with the side kick switch last night. Will be interesting to see if it fails on my way home later.

I wouldn't say that its always on closing the throttle ... mine seems to happen when I shift up from 1st into 2nd or even as far as into 3rd ... or thinking about it now .. might actually be when I close the throttle to shift into 2nd ... not sure :confused1:

I am booked into the dealership for next week Tuesday and they said they will keep it for the day, maybe they pick something up on the diags as I will not have received my GS911 before then ... Will let you know once I am any wiser.

__________________
--
London to Cape Town 2010 - http://bit.ly/uk2za

JUST A THOUGHT.....
could it be the same grief R1200GS owners had with the Fuel Pump ECU... number 14 on diagram? I wonder?

Temporarily resolved (in the absence of a spare) with the FPC (Fuel Pump Controller) bypass? it could be that it is 'not dead yet but dying'
Check the connections to it first!
if not,
WITHOUT destroying yours, it may well be worth trying the bypass to see if that solves the problem. It sounds complicated but it isn't
It consists of using the original blue plug that has 2 wires on it (on my 1200) and connecting a live to one and negative to the other and feeding electricity straight from battery
I do not know your bike but without cutting the wires, it may be worth scraping naked each wire and trying this- If it does not work, then tape up again.

If there are no plugs and if the fpc plugs directly into the unit, might be worth taking out the FPC (14) and carefully (you don't want a short) putting a 12volt supply to the terminals.
The result of a FPC bypass is that your fuel pump will :
1- run continuously
2- less fuel economy

If this method is successful - it would be useful to put a switch or in line fuse that you can remove to turn the pump off manually.

That won't give you a definitive answer and at the moment you need to concentrate on eliminating possible problems in order to narrow down the field.

Remove the side stand switch completely. You disconnect the switch by using an 8mm socket on the nut at the bottom, then it comes loose. It's a bit like a coiled watch spring. There's a stud that rotates with the stand. All you do is to experiment to find out what positions it runs in, then gaffer tape the stud in the middle of the settings.

If you are talking about white residue on the aluminium heat sink, this is to be expected.

There's only been one recorded occurence of a fuel pump failure on a F800xx bike and the symptoms are totally different. If you want to see how I bypassed a 1200GSA, checkout post #24 on this AdvRider thread (which doesn't need a switch to control it).

Tim

__________________
"For sheer delight there is nothing like altitude; it gives one the thrill of adventure
and enlarges the world in which you live," Irving Mather (1892-1966)

ok so today i disconnected both the O2 sensor which i think is the same as the lambda sensor, and the air temperature sensor (the one sticking out of the airbox).

i did NOT unscrew the O2 sensor from the exhaust - its 22mm and the largest spanner i have is 21mm - i don't reckon i need to remove it, unless the cat is blocked which i highly doubt given exhaust pressure & nature of fault.

managed less than 4km before the bike stalled...

i continued on & changed the oil & oil filter (was due). return to camp stalled another 4 times in 6km.

gonna disconnect the side stand now. not confident but seems to be a common problem.

next i will try disconnecting the idle actuator valve.

i've already tried to bypass the fuel pump electronics & the bike ran worse. however maybe i fkd it up so i will try it again this afternoon.

either today or tomorrow i will track down a car battery & leads to throw on the rear rack & try running the bike from this, maybe its the dead battery cell even with a 13+v reading on the multimetre.

apparently there is a bmw car dealer in north khartoum. think its too far for the bike to make it but i'll check it out with a taxi & see if they have a computer.

thanks for your continuing support guys.

dave

Hi Dave .. good luck for today. Check this video (if you can): YouTube - F800GS Stalling

I emailed this guy and for him it was his fuel pump ... extract from his email below:

"....Mine was all about hot temperatures and turned out to be a bad fuel pump NOT fuel pump electronics. It was only detected when I rode the bike around for an hour in the Denver heat until it started to stall and the tech put a pressure gauge on it. He found that it was spiking and dropping uncontrollably. New fuel pump and all's been well but was a real challenge for me to get them to diagnose it."

Let us know how you get on ...

__________________
--
London to Cape Town 2010 - http://bit.ly/uk2za