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Andy949494

Joined:

Feb 08

Posts: 817

Andy949494 says:

Stalling when coming to a stop. Dodgy Fuel?.

I haven't been able to ride my bike recently so as the weather was nice I took it off the trickle charger, checked tyre pressures etc, fired it up (eventually it took a while to start) and rode it on News years Eve.
I stopped after 30 miles filled it up with Tesco fuel and carried on.
It was going really well for forty miles or so and I was really enjoying being a biker again until I was changing down slowing up for a roundabout when it stalled (and I went sideways eek). It did restart after I pulled the clutch in but after that it was pretty much stalling every-time I pulled the clutch in if the revs were below 3000 revs or so (I had to artificially hold the throttle open as I changed down to keep it going). Got to work and had a quick look at the breather pipe which was dirty but seemed okay and passed a wire through it to check....  
Going home I had a right game with it. It took several goes to start (very unusual) and then died every-time the revs sank below 3000 again making the journey really nasty. Even at traffic lights etc it wouldn't idle smoothly so I sat there with the revs up at 3000 like a right idiot...
When I got home it again coughed and spluttered as i changed down but I restarted it and then it ticked away happily at idle as if nothing was wrong after I had parked it!
The bike is an F800S and it did have a new Fuel Pump & latest electronic update about 18 months ago for something similar (Last time it started stalling when changing down occasionally when the fuel was below half (the fuel tank is lower than most bikes) and then it got progressively worse) but before I book it into the dealer is it possible that this could be dodgy fuel - specifically I suspect it might have water in it - since the weather has been rather wet?
Again my other suspicions would be things like HT leads but it wasn't incredibly wet (light rain) and always restarted again almost immediately - my alfa (which had ht type problems)  used to die for ages when wet ...
Thanks for your attention,

Andy

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  • Posted 2 years ago (02 January 2013 16:23)

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James600zx

Joined:

Sep 07

Posts: 2767

James600zx says:

Hello Andy,

Not sure if it's relevant but just to clarify, did you make 10 miles after the fuel stop, or 40 miles?

How's the battery?

I'm also wondering if the final restart (when it ticked over nicely afterwards) was made with a full electrical reset (turn of the key) in contrast to earlier when perhaps you left the ignition on and just hit the starter button?

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Andy949494

Joined:

Feb 08

Posts: 817

Andy949494 says:

Further info/clarification...

Hi James,
Before filling I had no clue of any problems. I had had to slow down and go around roundabouts etc to get into the petrol station and had no problems. I filled it with 8.31  litres (capacity is approx 16 but my journey is 115 miles so I have to fill-up every day).
After refilling I had done about 10 miles when i first noticed the problems - the road after refilling is a  fairly boring dual carriageway with one roundabout after a mile and then I kept a constant 70 with a few hills, corners, speed cameras etc until another  roundabout about 9 miles on.
The battery SHOULD be great. It was replaced about a week before I stopped using the bike (so about 4-5 weeks ago) and it has been on a trickle charger.
The final restart was made with a key but before I set-off home (from work - after looking at the breather tube etc) the bike had been left for six hours or so (sorry omitted that) ...
I will try and restart it again this weekend (This is why I 'm not using it much since it lives away from me at the moment...)

Andy

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James600zx

Joined:

Sep 07

Posts: 2767

James600zx says:

Stalling when coming to a stop. Dodgy Fuel?

"Got to work..."
Ah yes, sorry, I missed that bit.

I don't subscribe to the idea that supermarket fuel is crap (I know you didn't say that), although it might have been true a few years ago. Besides, I believe BMWs have the smartest electronics for dealing with varying qualities of fuel.

If rain water has somehow got into the tank try a splash of methylated spirits (ethanol) or a fuel additive like Silkolene Pro-FST to flush it out.

Modern petrol has up to 5% ethanol in it anyway which might be enough to do the job. I recently made the mistake of letting a good few mls of rain water into my R1's tank (the cap drain hole must be blocked) and it didn't make any noticeable difference, although there was already Pro-FST (as a fuel stabilizer) in there due to a few weeks inactivity.

I always suspect the battery/charging system first, so was the new battery topped up by a charger before use (well worth doing to get 100% fitness) or did you add the acid and then just connect it to the bike? Is the trickle charger you refer to some sort of smart charger or the solar-panel and inverter combo I've seen you refer to (-and which I had a go at copying)? Not much sun lately! Is your charging system OK?

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jaffa90

Joined:

Mar 09

Posts: 8828

jaffa90 says:

stalling

It`s a common problem on this model and dangerous,

http://www.google.co.uk/search?hl=en-GB&source=hp&q=2007+bmw+800s+stalling&gbv=2&rlz=1R2NDKB_enGB509&oq=2007+bmw+800s+stalling&gs_l=heirloom-hp.3...3455.22702.0.23513.22.22.0.0.0.0.178.2402.12j10.22.0...0.0...1c.1.1hegBjbxAto

When you release the fuel cap after stopping can you hear any vacuum noises?

Is it possible/easy/safely to remove a spark plug after it stalls and comes to a stop (dry/wet plug)?

When it comes to a stop are you switching off and then back on to prime the fuel pump?

[This Reply has been modified by the Author]

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Andy949494

Joined:

Feb 08

Posts: 817

Andy949494 says:

Further info.

Hi Jaffa, James,
I did have a very similar issue and had had it fixed 18 months ago by a new fuel pump and software update and was hoping desperately that my fuel pump hasn't died again... As you say its very dangerous and scary and completely wrecks your enjoyment. The bike does restart from the button whilst coating to a halt and doesn't need the key position changing...
I don't appear to have a problem with the breather - When I open the fuel cap there is no noise etc of air rushing in and I had a good rootle around it as well and couldn't see an obvious blockage.
 I don't usually attack Tesco for their Petrol Quality. I have used it for many miles on many different bikes (and cars) since I like their self-service pumps.  However I did wonder if they had an ingress of water into their tanks with the heavy rain - I did have a problem with a car a few year (maybe 10!) ago that cleared up itself but it was a little more benign (coughing and spluttering rather than outright stalls)...
The bike was left with about 3/4 tank of fuel in it so one might expect problems from that old fuel but it seemed to only start after refilling. The F800 tank is plastic so I don't need to worry about rust :smile
It did take a while to start the first time but it wasn't enough to flatten the battery - hope its not possible to kill the pump this way (as its clearly not got petrol in it initially). It shouldn't be but the F800 does have a weak pump to start with...
The battery has been on my "own brand" solar trickle charger. Although this is obviously a risk since it doesn't do a very good cycling (it trickle charges when needed when the sun shines) at the moment its not my main concern as the bike turns over very sharply with the starter and the instruments don't reset - a quirk of F800s. This is the longest I have left any of my bikes - sadly although my old Kawasaki 250 needed a trickle charger to last a weekend - I think it was the heated grips this one takes a little longer to get down that far)
I'm very interested in getting a fuel treatment/stabilizer - as a cheap and easy option to try before I book it in.  I would try replacing the whole tank of fuel but its not easy to dispose of 10 litres of (dodgy) fuel...

Andy

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Andy949494

Joined:

Feb 08

Posts: 817

Andy949494 says:

For the record...

It was the Fuel pump wiring harness. Got it into the dealer in March and the diagnostics showed the fault straight away. Fuel was absolutely fine. Completely changed bike on the way home.
Not doing a lot of riding at the moment. Changed jobs and too busy at the weekend...
Andy.

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