Idle speed control valve control system

An engine for a watercraft comprising a cylinder body, at least one cylinder bore being formed in the cylinder body, a piston being mounted for reciprocation within the cylinder bore, a cylinder head being disposed over a first end of the cylinder bore, a crankcase member being disposed over a second end of the cylinder bore, an output shaft being disposed at least partially within a crankcase chamber at least partially defined by the crankcase member, the output shaft powering an output device, a combustion chamber being defined at least partially within the cylinder bore between the cylinder head and the piston, an intake conduit communicating with the combustion chamber, a throttle valve being disposed within the intake conduit, a throttle valve sensor being capable of sensing a position of the throttle valve, a bypass passage communicating with the intake conduit at a location between the throttle valve and the combustion chamber, an idle speed control valve being disposed along the bypass passage, a speed sensor capable of deducing a traveling speed of the watercraft, a controller electrically communicating with the idle speed control valve, the speed sensor and the throttle valve sensor, the controller being adapted, when the throttle valve is rapidly closed, to close the idle speed control valve a first rate when the watercraft is traveling at a speed greater than a preset value and a second rate when the watercraft is traveling below the preset value.