The problem is not the OEM stuff, it's the repro cr-p that doesn't work correctly out of the box. trying to calibrate them to ready full and empty is typically a time consuming experince that results in settling for a gauge that reads somehwere near
1. full when full, but 1/4 tank when empty
or
2. between 3/4 and full when full, but empty when empty.

It all has to do with the resistance wire used and the number of turns on the board inside the sending units variable resistor. Not rocket science by any means, just cheap manufacturing.
I have the reason and explanation why this is but cannot post it as it is likely too be considered to racial.
maybe when I retire soon I will look into correcting this issue. But how many are willing to pay 200.00+ for a correct reading unit ?