Hi Graham.
It is not a floater problem, it is a defective indicator. You typically get the indicator going down, in some case the light comes on, then the indicator goes up again. Guzzi is aware of the problem. The problem is fixed replacing the console.
There is a technical service bulletin on the problem, here an extract:
"MOTO GUZZI BREVA 1100:FUEL SYSTEM, OTHER:STORAGE:FUEL GAUGE SYSTEM
MOTO GUZZI BREVA 1100 2006 Safety Report #TB-011-2008
MOTO GUZZI BREVA 1100 2006 technical service bulletin was issued Nov 21, 2008.MOTO GUZZI BREVA 1100 2006 had a failed FUEL SYSTEM, OTHER:STORAGE:FUEL GAUGE SYSTEM . MOTO GUZZIE MOTORCYCLE: FUEL LEVEL INDICATOR. THERE IS A NEW CODE AVAILABLE IN OUR SPARE PARTS CATALOGUE REGARDING THE FUEL LEVEL INDICATOR FOR THE MODELS SPECIFIED (BREVA 850/1100/1200, NORGE 850/1200, 1200 SPORT, STELVIO). "
Find the nearest Guzzi dealer and ask. They will propose a console replacement and tell you the terms and conditions of repair. Mention the DTC above, the problem is a factory defect.
Regards.
Ginko (Proud owner of 5 Guzzi! :) )