Update Albeit Late
Sorry for the late update. My last post was in May 2008 after which I rode to the Isle of Man TT races with the bike's fuel gauge still malfunctioning. In late July 2008 I went to the dealer in Kaiserslautern, Germany, where I bought my bike. The sales representative had me come in to explain and show my problem to a BMW AG motorrad engineer, who was visiting for the day. I explained the symptoms of the problem and told the engineer that I thought the problem was either a sensor or the software based on my experiences on other vehicles. That might have been a mistake on my part as it might have led the engineer to only check those two items when in fact something else identified had he trouble shot the entire system. Interestingly the BMW AG motorrad engineer stated that this was the only fault of its type the company had a record of for the 2008 R1200GSA. Hmmm. The BMW AG motorrad engineer instructed the dealership to verify the software, which they did and it was the most current at that date. Then the BMW AG instructed the dealership to replace the fuel sensor, which is in the left side tank. The dealership filled the tank to full and then I rode back to Aschaffenburg, 101.3 miles later. The fuel gauge read full the entire time. In fact for the next week it behaved exactly as it had before. I wasn't sure what the problem was. I thought that maybe the newly replaced fuel sensor might have been defective as well; I really didn't know what to do. I passed all of this information to the Kaiserslautern dealership.
The Kaiserslautern sales representative let me know about a week later that there was a new software drop that might address the problem and asked me to bring the bike in. The sales representative was more than a little frustrated that the BMW AG motorrad engineer did not inform the dealership of the upcoming software update. I find this hard to believe that the BMW AG motorrad engineer didn't know this either when he was visiting the dealership the week prior. All software releases by any company or program have a target date for release and certainly field engineers would be informed of what the software was going to fix and what capabilities would if any be added. Anyway, I rode to Kaiserslautern a week later, on or about 12 August 2008 and had the new software loaded into the bike. According to the Kaiserslautern sales representative who worked with me on this problem from the beginning my bike came with software Cip10, was then updated to Cip11 (at some point, possibly the first service), and then to Cip12 which apparently has fixed my fuel gauge problem. I say apparently because, although the fuel gauge now works properly I haven't put on as many miles/kilometers since due to my job. I have had one hiccup in which the gauge read an improper amount but after shutting the bike off and restarting it worked. I'm still baffled because I really don't know what caused the problem. At first there were a number of posts on the afore mentioned websites describing fuel gauge problems but only a couple that appeared to be the same as mine. Now there doesn't appear to be hardly any posts on the subject. Maybe the issue is solved or the owners have given up and live with it. I suppose I might have had corrupt software, but I'm not sure.
As a side but related note, one of the times when I took my bike in for this problem the dealership's owner let me borrow his bike for while mine was in the shop. When I got on his bike, a 2008 R1200GS, the fuel gauge indicated that he was on reserve. I took the bike to a fuel station and filled it up. After I filled up his bike I figured he had at least 8 liters of fuel when the fuel gauge starting flashing. Hmmmm. I did pass this information onto him.
Sorry for the late update. I'll continue to update if there are any other issues with my fuel gauge, but as for now it seems to be working fine.