*Need help on how to wire up a switch panel*

If it fires on the starter and dies, it is probably not getting "run" voltage. That is, it is firing on the bypass circuit (brown wire) feeding the ignition during start, and losing voltage for some reason when you release the starter.

Again, with this modification, I'm guessing. You should be able to put your switch in "run" with the engine off, and check for voltage at the regulator and ignition.