The 0/0 is a really cheesy per-cent sign.
There is a discussion about how to (slightly) improve the fuel gauge by changing to a 280mm sender with a correcting shunt resistor
in this lengthy thread.
Are you SERIOUS??? 0/0 is a percentage sign??? Well thank you for solving that mystery. I am not going to go to great lengths worrying about the gauge. I will start by finding a comfortable mileage and use the tripometer as my gauge. Done it for so long on other things that it is no big deal.