Patent ID: 7077713

Claim:
A system for controlling a speed of an internal combustion engine installed in an outboard motor mounted on a boat and having a propeller powered by the engine to propel the boat, the engine having a throttle valve that regulates air to be sucked, comprising: an actuator connected to the throttle valve to move it in an opening direction or in a closing direction; engine speed detecting means for detecting the speed of the engine; engine trouble detecting means for detecting a trouble occurred in the engine; engine speed discriminating means for discriminating whether the detected engine speed exceeds a predetermined speed which is larger than an engine idle speed when it is detected that the trouble has occurred in the engine; and actuator driving means for driving the actuator to move the throttle valve in the closing direction such that the engine speed drops, when it is discriminated that the detected engine speed exceeds the predetermined speed, wherein the actuator driving means drives the actuator to move the throttle valve in the closing direction by an amount repeatedly such that the engine speed is gradually lowered to the predetermined speed.