1976 Scamp fuel gauge problems

For the most part I understand how the gauge works, but I figured it was worth a try. There's a post around here somewhere stating that running 7 volts through his gauge got it working how it should, but since mine did at least read full, I figured why not try 6 and see what happens. Now I know that it just delays how long it takes it to get to empty. When still on the mechanical regulator, it would read empty after four gallons, on the electronic one that puts out one more volt, it reads empty after about 6-8 gallons.