US Patent 7077713 Engine speed control system for outboard motor

In an engine speed control system for an outboard motor having a throttle valve that regulates air to be sucked and an actuator connected to the throttle valve to move it in an opening direction or in a closing direction, the actuator is driven to move the throttle valve in the closing direction such that the engine speed drops, if it is discriminated that a detected engine speed exceeds a predetermined speed (set to a speed at which the engine can assumably continue to run until the boat has returned to port), when a trouble has occurred in the engine. Thus, the system can lower the engine speed so as to allow the boat to return to port, without causing the engine to vibrate, when a trouble has occurred in the engine.