f650gs twin power failure
 

Cruising in to Vientiane Laos, done 150+ km on the tank, and lost power. Pulled over to the side and cursed for a minute. Computer read over 100km fuel remaining. Turned key off, then on and ignition. Bike started but problem re-occured twice more (every 500m or so) til I made it to a petrol station. Suspected computer was wrong, but tank only took 10L to fill meaning 6L was still in the tank. Bike has been okay for about 5km 'til I made it to the hotel...

Any suggestions? I guess not fuel pump because bike was still running, dirty fuel would have presented earlier I thought? No BMW dealer in these parts for help...

Thanks in advance.
Dave

Water in the fuel?

Settles after a fill up and accumulates at the bottom of the tank, and then starts playing havoc with the injectors as it passes through to the cylinder in larger quantities ....

Otherwise dirty fuel would still be wurth considering. Does it have a fuel filter in place?

Start with the easiest explanations first...

Power loss on F800GS
 

Hi Dave,

I'm currently in Bolivia with what sounds like an identical problem on my F800GS.
It first occured in Argentina over a week ago, 30 degrees midday temperature with 30km remaining showing on the OBC. I filled with fuel and all was good until a couple of hours later (with > 180km remaing on OBC). It got worse so I stopped for the day.
The next morning the problem did not occur (it was only 20 degrees). However it re-occured later in the day as it rose to 30 degrees, again with plenty of fuel in the tank).
This is all with easy cruising at 100km/hr.

There's a lot of stuff on ADvRider & other forums. I'm guessing that the fuel pump and/or fuel pump electronics is giving up at high temperatures (the pump is cooled by the fuel in the tank), so I'm carrying 4 litres of reserve fuel and continually refuelling, which seems to be working. Also, I'm now up on the altiplano at 2000-4000m so it's a bit cooler.

I too am nowhere near a BMW dealer. I emailed all five dealers in Argentina a week ago asking if they had replacement fuel pump parts, but guess what - none have bothered to reply. I spoke to a BMW service guy in Sydney, but he hadn't come across this before.

I'm staying put here for 2 or 3 weeks. I'm thinking of fitting a small 12V fan beneath the seat which could cool the heatsink on the fuel pump electronics. However, I don't reckon this will help if it's the pump that's faulty.
Let me know if you find a solution.

Anton.

dajg: It could be the sidestand switch, read my thread on UKGSer. I never got a proper resolution to the problem, several months later I was recovered to a dealer whilst on my way to Poland and they totally removed everything and connected the wires together.

delta8: The heatsink under the seat is on the top of the fuel pump controller which is a little device that controls the actual pump and saves it having to work permanently at 100%. If the FPC burns out it's normally a permanent failure (and one which is a bugbear of 1200GS owners), so I doubt it's part of your problem. I'm aware of only one FPC failure on a F650/800GS against many hundreds of failures on the 1200GS/GSA.

I also can't see that temperatures of 30c should be part of the problem, maybe if it was the high 40s...

Tim

Hi Tim,

On one of the forums I came across an F800 stalling problem which was down to a fuel pressure sensor failing at high temperatures. I assumed it was part of the pump electronics - any ideas?

Another user reported his dealer saying a Hall Effect sensor was failing at high temperatures - I assume this is part of the fuel pump motor?

cheers,
Anton.

I've not heard of either of those. If you haven't already done so, I'd suggest posting on UKGSer 650/800GS forum and F800 riders 650/800GS forum.

Tim

I posted my original problem on advrider the same time as hubb - they seem to get back quicker with technical problems see link f650gs twin power failure - ADVrider there were a few ideas I never heard of before.

Anyway, I am now in Chiang Mai & I went to the BMW dealer here to use the computer to run diagnostics or whatever but no error message came up. I had thought maybe the computer over-road the engine to protect itself i.e. low oil or something? The problem hasn't reocurred since I filled up in Vientiane, about +1500km ago now.

I can only guess it was dirty fuel or water. I never added metho to soak up water (my original idea) because a motorcycle guy in Vientiane (Jim @ Remote Asia Travel) reminded me not to fix what ain't broke. Also I never drained the tank, filtered or tested any fuel etc. I ran the fuel down to <20km or so to see if there was any remaining dirt in the tank to stop the engine again but it was all good.

Still have +30,000k left on this journey, so if it comes up again I let you know. Good luck sorting it out in Argentina.

D

Is the tank vent ok? If the venting is blocked, the pump will produce a low pressure in the tank that becomes lower with consumption and eventually the pump can't overcome the low pressure. If you then stop and look in the tank, or fill it, normal pressure is restored and the cyclus starts again.

I don't know your BMW but some bikes have a valve in the lid.