Abstract: An ignition system for a fuel burning engine is provided connected to and from a battery, a coil, and a starter motor. A protection circuit having pressure and temperature sensing switches has relay contacts in series with the coil. The relay contacts open when abnormal running temperatures and pressures occur to shut down the engine. During startup, a battery voltage is supplied to the coil through a conventional key operated switch and in response to the energization of the starter solenoid. The latter makes possible the elimination of an undesirable prior art bypass switch.