Turbo miata won't start every time
 

I have a 1991 miata with a 1995 turbocharged 1.8 motor and megasquirt ecu. The car will start every time when cold. After a drive, usually a short one, the car will not start. When the key is turned you can hear one click from the engine bay, but motor does not attempt to turn over, everything is silent. All while, the AFR gauge flashes 7.4 and the battery light stays on. After about 45 seconds the car starts up as if nothing ever happened. Has this ever happened to anyone else? Previous owner installed engine cut off switch and a push to start button, could this be causing the problem? Thank you to everyone in advance.