if the fuse is ok then i think the sender arm / float has fallen off, its a common problem with the older cars.
It has a pressure clip holding the arm on the guage/frame.
The clips fallen off and is probably sitting in the tray under the sender unit, the float arm will be nearby, which is why u need a near empty tank, cos sticking ur arm in a full tank of fuel isnt safe or fun!
the clip needs fishing out and flattening slightly so it grips better and refitting on the end of the float arm once its reinserted in the sender frame.
(its that or spend £150+ for a new sender unit+fitting.)
You will need to run the tank nearly dry (carry a spare gallon can of fuel)
Then take it to a indy garage (they may have the special tool (£50 avaialble only from renault dealerships) to take the ring off the sender unit)
or risk taking it off with a screwdriver/hammer, but your gonna probably break some of the lugs on the edge of the ring(i did
you need to be carefull releasing the fuel pipes, run the car and pull the power lead off the sender unit, that will depressurise the fuel lines.
a new sender ring/gasket kit is recomended when changing or removing it (about £15 or so from renault)
there is a 30 min time limit on having the tank open, dont ask me why but they distort if opened for more than a few minutes, so do the job quick!
and make sure you dont over tighten the ring or the gasket will distort and fold into the tank.
when i did mine i suffered a filler unit failure shortly after, with petrol leaking from a cracked seam half way up the filler unit, though i have no idea if it was related in anyway to the opening up of the tank or when the tank straps were replaced.
just keep a eye out for the smell of petrol or damp patches around the tank.