There are two diodes in the circuit before the solenoid with the black rubber top.
They are connected to one of the small wires on the solenoid.
These diodes prevent the engine from starting and stopping at the same time.
If there is a short in the diode the engine will try to start and stop at the same time.
The diodes are made by Motorola and are not immediately visible as they are covered by black heat shrink tubing.
They are a few inches from the big solenoid.
One of the wires goes to the starter switch and the other goes to the stop solenoid in the injector pump.
The first thing I would do is to check the diodes.
Amel Super Maramu #376
I am unable to stop the engine with the switch button in the cockpit
I have to use the manual stop button (red one ) inside the engine.
Despite having changed the relay (solenoid ??) and the switch button on the helm, no technician have been able to find the solution. It seems that the small relay that control the big relay that connects the minus is taking two contradictory messages : to start and to stop.
Do you have any idea or recommendation.
Thanks in advance.