On my Westerbeke
, the line to the engine ignition switch is supplied by a 20-amp push-button circuit breaker mounted on the engine, near the preheat solenoid. Is that the breaker you mean? If that circuit breaker opens on the W46, the engine will stop, but some other engines can continue to run without that circuit energized.
There is also a 10-amp self-resetting circuit breaker mounted onto a flange of the preheat solenoid, which is only used to bypass the oil-pressure switch. It supplies power to the preheat solenoid coil, the fuel
cutoff solenoid, the injection pump
and the instruments during the preheat phase. That circuit breaker can open while the oil
pressure switch is closed and the engine is running and will affect only some of the instruments.
If you need some more help, send me a PM with the details of your trouble-shooting.