I think the 787 does tend to run a little fat in some throttle positions, this is normal.
Sending units are a series of magnetic reed switches, some floats have two magnets on them I believe, could be either one of the magnetic reed switches isn't closing, a magnet has dropped off the float or the hollow plastic float has a small hole and is partially full of fuel.
My sending unit stopped working again last year, need to yank it again and see what's going on.