I have just purchased a new to me 2003 R1150RT.
I have found the fuel level indicator on the RID unit to be somewhat unreliable. On my first trip I noticed that it only dropped about two bars and then no change. But later on the ride I noticed that the indicator started working, and I watched the bars, now indicating lower, light up and go away as I went down a pretty good hill and back up the other side. After we stopped for a break it was back to the original two bars down. I have not run the tank down far enough to get a low fuel light as yet.
I have both a Haynes and a Clymer book and in looking in them they show a float type indicator attached to the pump filter assembly. When I go to the online parts fisch, It shows an additional tube type sender that attaches from the top of the tank. This sender is not indicated in either of these two books.
So, what do I have? And then what can I do to fix it? I am coming off of a K1100 and it is an entirely different animal.