I have fought the problem of trying to match a different sender value to gauge several times without much if any succcess. The only ways I know to change it is to put resistance in series or parallel with the sender. Neither works well. The series resistance moves the needle up or down on the gauge face depending on if it 0-? or ?-0 ohms. Putting resistance in parallel puts in why too much non linearity.
Another way I have not tried, but may work, is to put some resistance in parallel with one or both coils in the gauge itself. Your nephew can 'breadboard' this quite easily and see if it works.
If you have a fresh tank then, as written above, the best idea might be to modify your tank to fit a correct ohm sender. Hot rodder's do it all the time.
Please understand, I made my living doing instrumentation. Gauges that read incorrectly are of no use to me. Others find that close is good enough, just not me. I try to live with the motto, "It will be just fine as long as it's perfect".
Last edited by beltfed; 01/02/2017 1:37 PM.
