Haven't read the whole string in detail, but you mentioned that you hooked up a household light switch to act as an ignition switch. I would look towards that as your problem. Could you have set it down on metal somewhere to where the terminals are touching grounded metal? Could you have possibly hooked something to the ground terminal? If so the entire metal case touching metal would ground out the circuit. I would try to ditch that switch and even just twist the wires together to see if you have the same problem. Just a thought.
