Combustion air intake ports are provided on left and right side faces of an upper part of an engine cover. An outer louver is disposed to confront the combustion air intake port, and an inner louver is disposed inward of the outer louver at a predetermined interval to face the outer louver. The combustion air received from the combustion air intake port passes through the outer louver and the inner louver and is guided to the engine unit from the guide hole. In this case, a splash of water is dispersed in the outer louver, and a large-sized water droplet falls down due to its self-weight before the combustion air reaches the inner louver, so that a small-sized water droplet can be collected and removed using inertial impaction at the inner louver. Therefore, it is possible to effectively separate water.

Embodiments for diagnosing a humidity sensor are provided. One example method comprises, responsive to a humidity sensor test cycle, pumping air conditioning and windshield washer gas flows past a humidity sensor, and indicating humidity sensor degradation based on a response of the humidity sensor to the air conditioning and windshield washer gas flows. In this way, degradation of the humidity sensor may be indicated if the humidity sensed by the humidity sensor does not change responsive to the humidity sensor test cycle being initiated.

A cover structure of an upper unit in which a power source of an outboard motor is provided, the cover structure includes a main body cover including a pair of divided covers connected to each other, the pair of the divided covers being configured to be divided into each other in a left-right direction with respect to a traveling direction of a boat, and an attachable and detachable cover that is attachable to and detachable from a part of an outer surface of at least one of the pair of the divided covers.

A marine engine assembly for mounting to a watercraft is disclosed. The marine engine assembly has an engine unit, an exhaust system fluidly and a propulsion device. The engine unit includes an engine unit housing, an internal combustion engine and an air intake assembly. The air intake assembly, at least one combustion chamber, and the exhaust system together defining at least in part a gas flow pathway. A sealing valve is provided in the gas flow pathway. The sealing valve has an open position permitting flow of gas therethrough. The sealing valve has a closed position preventing flow of gas therethrough for sealing a portion of the gas flow pathway downstream of the sealing valve from a portion of the gas flow pathway upstream of the sealing valve.

A cover structure of an upper unit in which a power source of an outboard motor is provided, the cover structure includes a main body cover including a pair of divided covers connected to each other, the pair of the divided covers being configured to be divided into each other in a left-right direction with respect to a traveling direction of a boat, and an attachable and detachable cover that is attachable to and detachable from a part of an outer surface of at least one of the pair of the divided covers.

A cover structure of an upper unit in which a power source of an outboard motor is provided, the cover structure includes a main body cover including a pair of divided covers connected to each otter, the pair of the divided covers being configured to be divided into each other in a left-right direction with respect to a traveling direction of a boat, an attachable and detachable cover that is attachable to and detachable from a part of an outer surface of at least one of the pair of divided covers and that includes a light transmitting portion in at least a part of the attachable and detachable cover, the light transmitting portion configured to transmit light, and a light emitter that is provided at a mounting position of the attachable and detachable cover and that includes a light source.

In an outboard engine including a throttle body that feeds combustion air that is taken in from an outside air introduction port, into an engine body, an intake duct that guides the combustion air from the outside air introduction port, and an on-off valve disposed partway in the intake duct, a plurality of paths are provided in the intake duct, a path of the intake duct is made switchable to a long path including a drainage effect to water entering the intake duct and a short path that does not include the drainage effect by the on-off valve, and the long path is selected at a time of an engine being stopped or a time of an operation state where the outboard engine is expected to be covered with water.

In an outboard engine including a throttle body that feeds combustion air that is taken in from an outside air introduction port, into an engine body, an intake duct that guides the combustion air from the outside air introduction port, and an on-off valve disposed partway in the intake duct, a plurality of paths are provided in the intake duct, a path of the intake duct is made switchable to a long path including a drainage effect to water entering the intake duct and a short path that does not include the drainage effect by the on-off valve, and the long path is selected at a time of an engine being stopped or a time of an operation state where the outboard engine is expected to be covered with water.

A cover structure of an upper unit in which a power source of an outboard motor is provided, the cover structure includes a main body cover including a pair of divided covers connected to each otter, the pair of the divided covers being configured to be divided into each other in a left-right direction with respect to a traveling direction of a boat, an attachable and detachable cover that is attachable to and detachable from a part of an outer surface of at least one of the pair of divided covers and that includes a light transmitting portion in at least a part of the attachable and detachable cover, the light transmitting portion configured to transmit light, and a light emitter that is provided at a mounting position of the attachable and detachable cover and that includes a light source.

An outboard motor includes an engine, an engine cover accommodating the engine, and an intake path between the engine cover and the engine. The intake path directs external air to the engine. The engine cover includes an upper cover and a lower cover. The upper cover includes an opening to take external air into the intake path. The intake path includes a first airflow passage, a second airflow passage, and an airflow space. The first airflow passage is at least partially defined by an inner surface of the engine cover, and downwardly directs the external air. The second airflow passage is at least partially defined by the inner surface of the engine cover, and upwardly directs the external air. The airflow space is above the lower cover and continues to the first airflow passage and the second airflow passage.