I had the partially collapsed fuel probe "syndrome" from a clogged charcoal canister that blocked the tank vent on my '99 I just bought. There's a bit of info here on the issue. The fix was a canister-ectomy.... as has been described often in the archives, and then pull the probe and repair it. It's an aluminum tube with an internal float and some wires on a "frame". When the tank doesn't vent properly from a plugged charcoal caniser, a partial vacuum in the gas tank causes the aluminum fuel level tube to partially collapse restricting the float movement.
I'm betting you have a version of this situation.....your fuel level tube is pinched near the top, and as your bike runs, fuel is drawn out of the probe to near the bottom due to plugged venting giving a near empty indication. Fixing the probe isn't too hard if you're a bit handy with ad hoc kind of repairs.
A simple test to see if something like the above is happening is to ride your bike for a while, stop, turn of the engine, and take off the gas cap. If there's an audible hiss....your tank isn't venting properly.
Good luck!
. Now this thread will likely get moved to the humor section.
