alien dash implant

when I got the car it had aftermarket mechanical gauges gauges.The fuel gauge did not work so I installed an Autometer gauge by splicing into I think a blue wire.I will see now if that gauge works.I can also hook up a temp gauge.The ammeter gauge does work but lately it reads a little high-just past halfway until a load(wipers,headlights) then it levels.I have 13.6 at battery and running about 14.6 volts so thats fine.I read to bypass the ammeter you remove the 2 wires and connect them and then run a voltmeter.Is that correct?
I'm not sure if the aftermarket fuel gauge will work with the factory sender, might be different values. Someone who knows more about that might comment. You are correct about the amp meter bypass.