Patent ID: 7717086

Claim:
A controller for a boat propulsion unit comprising: a switch arranged to switch between a long intake duct and a short intake duct to draw intake air into an engine of the boat propulsion unit; a motor-operated driver arranged to drive the switch; a duct length switching position sensor arranged to detect a position of the switch at the time of switching the duct length; a fuel supply arranged to supply fuel to the engine; a sensor failure detector arranged to detect a failure of the duct length switching position sensor based on an output from the duct length switching position sensor; and a controller arranged to compensate a fuel supply rate based on the switch position detected at the time of switching the duct length; wherein the controller switches to the long intake duct when the duct length switching position sensor fails, and compensates the fuel supply rate using a sensor output quasi value corresponding to the time of switching to the long intake duct.