My 2000 Chevy Impala fuel gauge reads empty.

Probably replacing the speed sensor on the transmission.Have the codes read, even if the light is not on. Look at the pending codes. The fuel gauge would be the sending unit in the tank. That act funny like that sometimes.

Probably fuel gauge sender in the tank or the fuel gauge in the dash.

Could it actually be empty? Did you forget to connect the electrical sending unit plug to the pump, under the car? Easy way to tell, remove the fuel line hose at the intake manifold, put it in to a container, try starting the car..if no fuel comes out, your pump is not working or tank is empty.

sounds like you need to change sending unit in the gas tank

Most likely you have a faulty sending unit in the fuel tank. The sender is a rheostat and can lose its electrical contact in parts of its travel distance from full to empty.

Problem 1: Dirty fuel injectors or fuel filter-----2nd problem: bad ground wire on --or going to the fuel tank.

take the sender unit out and check the float ,sounds like its full of petrol and not floating giving a reading of empty

You're either looking at a short in the wire that goes to the fuel sender, or a bad fuel sender. If it was just a broken wire, it would read empty instead. The fuel sender is a permanent part of the fuel pump, so that has to be replaced as a unit.

Youre gauge is controlled by a plunger in the fuel tank which is attached to the sensor and the fuel gauge. it sounds like when the plunger goes down half way its either getting stuck down lower then it should. Needs replacing. Any mechanic can do this install for you.

did you recently change the fuel pump? If so you needed to change the wire harness thats attached to the fuel pump, then if not, your floater need to be replaced inside your fuel tank.
How do I know? from experience.