Don't bother with a new sender.
It has to do with the fact that the float arm and sender are not engineered/calibrated to report the fuel level in direct proportion to the remaining fuel.
Aircraft are engineered to very very different standards. In general in the Aerospace industry, a set of fuel gauges on various types of aircraft are expected to work exactly the same. In addition, the engineers are very likely expected to produce a sender that compensates for the rate change in float arm travel as the fuel levels change. If the gauges read 1/2 tank, you can bet that you really do have 1/2 of your fuel supply remaining in that tank. If it doesn't it will be considered a bad design and unacceptable. I briefly studied Aerospace engineering before changing to Computer Science.
Then we get to quality... 99% of the time you won't die if you car breaks down. In an aircraft your odds are lower no matter how much experience you have. Cars are cheap, aircraft are not. You get what you are paying for!
Apples and oranges my friend!
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I hope to join you up in the air once I get around to taking lessons.
