Did you use a "digital" meter? Many have an "averaging circuit" to prevent the characters from flipping between digits, so it may not show the noisy rheostat (variable resistor sending unit). Just for curiosity, is the sender "immersed" in the fuel and how is the wiring routed?
Reason I asked is HD recently came out with a "Digital" fuel guage inside the replacement master cylinder cap. The sender and wiring is shown as replacing the existing "idiot light" sender, but no actual picture of the installation as to how it is fitted in the tank or the wire routing. Only that they have cable ties and molex type plugs and single orange wire to be spliced in.