mine goes the other way, shows empty when it has about 1/4 tank, and won't get much over 3/4 when full. seems like it should be easy to adjust, but i have set it so that it matches the factory ohm settings, and have played with adjusting the float, never comes out right.

1_wild_rt has a good point. i'm going to start looking for a used core and see if i can either use it as it is or have someone rebuild it.