Patent ID: 6983646

Claim:
An atmospheric pressure detecting apparatus for a four-stroke engine comprising a nonpressure regulator mounted on a pump for pressurizing fuel in a fuel tank for regulating an upper limit value for the pressure of fuel pressurized by the pump, a fuel injection device for injecting fuel the upper limit of which is regulated by the regulator into an air induction passageway of the four-stroke engine and an air intake control valve provided in the air induction passageway, the atmospheric pressure detecting apparatus for a four-stroke engine being characterized by provision of intake air pressure detecting means for detecting an intake air pressure downstream of the air intake control valve, operating condition detecting means for detecting an operating condition of the four-stroke engine and atmospheric pressure detecting means for detecting an atmospheric pressure from an intake air pressure resulting when the load of the four-stroke engine is small and immediately before an inlet valve opens based on the operating condition of the four-stroke engine detected by the operating condition detecting means and the intake air pressure detected by the intake air pressure detecting means.