Hi there, I though I would chip in. I've been around Africa, 75'000 km on the F800GS. I was carrying the FPC bypass cable but never needed it. The only problem I had with fuel, was that a few times when it was hot and with a near-empty tank, the engine would cut off completely. i chased it down to a problem with the venting of the tank: I could hear the air being sucked in when I opened the tank. Then it would start normally.

Eventually I took apart the little gizmo that blocks the venting hole when the bike is not upright, suspecting it could get stuck in the wrong position. It seemed to be ok so I put it back in and since then no problem anymore. Not that it had been very hot either, but so far so good.

Laurent

Fuel Pump
 

I have an F650gs twin, 2009 !!!!
Mine went in Africa after 24000 km, I just pulled it out in Mzuzu Malawi, & took around town to try & by the same one & eventually found a french made one that was exactly the same & has worked ever since.
I did have a thermostat go on the same bike after 12000 km as well.

Bypassing the fuel pump controller (FPC) is extremely easy to do. Unless you are color blind, keep that in mind.
The symptom of the bad FPC is that the bike simply wont start, and no whine from the fuel pump. The bypass requires only a multitool, you use the mole ends (needle nose pliers) to remove the two little T10 screws and pop off the FPC and the knife to bare the wires, and you will need some simple electrical tape or something to isolate the spliced wires.
REMEMBER: If your FPC is grey colored it will likely fail, the new black powdercoated ones supposedly don't.
Once you have removed the T10 screws, they are easy to get with the mole ends of the multi tool if you don't have a torx 10 key.
You will then pop the duff FPC off its base with the useless green gasket which is part of the problem. Look down inside the "well" and you will see a blue connector.
Pinch the the two ears of the blue connector in the "well" together and remove the duff FBC.
You then disconnect it from the black connector at the top.
remove some of the tape shield on the wiring loom to the black connector and you will see 3 wires.
Now is the point of no return.
You then must separate the blue connector from the duff FPC (but keep the duff FPC to make a future short bypass cable and save the money you would spend on the one that is advertised for more than $30, you can easily make one in a few minutes with the old duff FPC).
Ok, now, if you are color blind, you are screwed. You will see the black connector has three wires colored blue/red, brown, and blue/green.
Forget about the blue/red, just leave it alone.
Carefully bare a small loop of the brown wire and a small loop of the blue/green wire to prepare them for the splice.
Next, you will note the blue connector has a blue wire and a yellow wire.
Bare the ends of both.
Next, splice the blue wire into the brown wire and tape it up so now copper wire is exposed.
Then, splice the yellow wire into the blue green wire and tape it up.
Just leave the blue/red wire as is, don't screw around with it.
Start the bike and off you go.
Later, you can gut the duff FPC and connect the female connector to the blue connector you have spliced in place and you have a fuel pump bypass cable which is "plug and play".
Done.
Tim Cullis pioneered the splice method when he was stranded in Morocco or some place with a duff FPC. Thanks, Tim!
I copied this to my smartphone and fixed mine when it went tits up/lights out on me 200kms from my home here in Mexico, way back in a mountain town.
It will get you home.
Now, if it is the fuel pump, that is a different story.

Our 09 F800GS fuel pump failed in Kyrgyzstan last year with very similar symptoms as OP. Although the tank was under vacuum/pressure and would whoosh when the fill cap was opened, leaving the cap open did not seem to address the pump issues. We also bypassed the carbon canister, which did not fix the problem. We were able to find a Bosch branded replacement in Bishkek and swapping that one in did fix the problem so we took a second spare for the road. Our fuel filter (the metal can above the pump, not the mesh bag below it) may have been choked up with the residuals of bad central Asian fuel, however, since then we've ridden another ~20k km on the same filter with no apparent problems from it. So it seems the weakest component is the pump itself and this often first starts showing problems by overheating and cutting off after a hundred or so kms, especially with less fuel in the tank (though I did get it hot enough to fail even after a fresh tank of gas).

For future reference, I posted some more details about possible replacement pumps including the Bosch part that I bought (part # 0 580 453 453), where I bought it in Bishkek, area biker info, etc, here:

http://www.advrider.com/forums/showp...0&postcount=18
http://www.advrider.com/forums/showthread.php?t=822587

Hope this helps the next rider!