Are you sure the troubles are in the gauge display and not the float/sending unit? I ask this because I would always suspect a mechanical assembly before an electrical one. After I swapped my ECU my fuel gauge was reading incorrectly, it stayed at full for a while and never went all the way to empty more like 1/8. I ended up pulling the fuel float assembly out of the donor car and once installed the gauge read correctly. The float simply moves the wipers on a variable resistor as it goes through its travel. Very possible the resistor is dirty, corroded, or broken.