Abstract: A propulsion unit can comprise a propeller and an internal combustion engine for driving the propeller. The propulsion unit can include a gear switching device for changing a drive mode of the propulsion unit between a forward drive mode, a reverse drive mode and a neutral mode. A throttle valve can be configured to control an opening of a first intake passage of the engine, and an idle speed control valve can be configured to control an opening of a second intake passage downstream of the first intake passage can also be provided. The propulsion unit can also comprise a control unit for controlling the idle speed control valve, wherein the control unit is configured to bring the engine to a first target rotational speed when the propeller is in the neutral mode, and to a second target rotational speed when the propeller is in the forward or reverse drive mode, wherein the first rotational speed is greater than the second rotational speed.

Abstract: An engine has a fuel injection system and an idle regulating control valve. The idle regulating valve is initialized upon engine shut down by closing to a fully closed position such that a reference value can be obtained in such a position. Once fully closed, the idle regulating valve is opened to a predetermined position and a value is written into memory that indicates that the initialization procedure has been completed. During subsequent restart, if it appears that the initialization procedure has not been completed prior to attempted restart, fuel injection is temporarily suspended. The fuel injection can be suspended during a subsequent initialization, until the idle regulating valve is fully closed or for a predetermined period of time. In some less refined applications, the idle regulating valve can be initialized during engine start up regardless of whether or not it is initialized during engine shut-down.

Abstract: An outboard motor fuel vapor separator-venting system that vents fuel vapor from a fuel vapor separator through a vapor relief valve. The vapor relief valve allows vapor to gradually be delivered from the vapor separator to an air induction system depending on the amount of air entering the air induction system and/or engine speed. The vapor relief valve does not allow fuel vapor to vent from the fuel vapor separator to the air induction system when the engine is not operating.

Abstract: The control system establishes an engine warm-up protocol based, at least in part, on elapsed time from engine start. The control system provides a reduced reliance on engine temperature as a basis for determining an appropriate engine idle speed. The control system thus reduces the likelihood of unstable idling conditions when, for example, inadequate cooling water or extremely cold cooling water is being supplied to the engine.

Abstract: A propulsion unit can comprise a propeller and an internal combustion engine for driving the propeller. The propulsion unit can include a gear switching device for changing a drive mode of the propulsion unit between a forward drive mode, a reverse drive mode and a neutral mode. A throttle valve can be configured to control an opening of a first intake passage of the engine, and an idle speed control valve can be configured to control an opening of a second intake passage downstream of the first intake passage can also be provided. The propulsion unit can also comprise a control unit for controlling the idle speed control valve, wherein the control unit is configured to bring the engine to a first target rotational speed when the propeller is in the neutral mode, and to a second target rotational speed when the propeller is in the forward or reverse drive mode, wherein the first rotational speed is greater than the second rotational speed.

Abstract: An outboard motor fuel vapor separator-venting system that vents fuel vapor from a fuel vapor separator through a vapor relief valve. The vapor relief valve is located in a high position on the outboard motor to ensure that liquid fuel does not reach the vapor relief valve. The vapor relief valve allows vapor to gradually be delivered from the vapor separator to an air induction system depending on the amount of air entering the air induction system and/or engine speed. The vapor relief valve does not allow fuel vapor to vent from the fuel vapor separator to the air induction system when the engine is not operating.

Abstract: An engine has a fuel injection system and an idle regulating control valve. The idle regulating valve is initialized upon engine shut down by closing to a fully closed position such that a reference value can be obtained in such a position. Once fully closed, the idle regulating valve is opened to a predetermined position and a value is written into memory that indicates that the initialization procedure has been completed. During subsequent restart, if it appears that the initialization procedure has not been completed prior to attempted restart, fuel injection is temporarily suspended. The fuel injection can be suspended during a subsequent initialization, until the idle regulating valve is fully closed or for a predetermined period of time. In some less refined applications, the idle regulating valve can be initialized during engine start up regardless of whether or not it is initialized during engine shut-down.

Abstract: The control system establishes an engine warm-up protocol based, at least in part, on elapsed time from engine start. The control system provides a reduced reliance on engine temperature as a basis for determining an appropriate engine idle speed. The control system thus reduces the likelihood of unstable idling conditions when, for example, inadequate cooling water or extremely cold cooling water is being supplied to the engine.

Abstract: An outboard motor fuel vapor separator-venting system that vents fuel vapor from a fuel vapor separator through a vapor relief valve. The vapor relief valve allows vapor to gradually be delivered from the vapor separator to an air induction system depending on the amount of air entering the air induction system and/or engine speed. The vapor relief valve does not allow fuel vapor to vent from the fuel vapor separator to the air induction system when the engine is not operating.

Abstract: An outboard motor fuel vapor separator-venting system that vents fuel vapor from a fuel vapor separator through a vapor relief valve. The vapor relief valve is located in a high position on the outboard motor to ensure that liquid fuel does not reach the vapor relief valve. The vapor relief valve allows vapor to gradually be delivered from the vapor separator to an air induction system depending on the amount of air entering the air induction system and/or engine speed. The vapor relief valve does not allow fuel vapor to vent from the fuel vapor separator to the air induction system when the engine is not operating.

Abstract: A marine engine is controlled to operate in a lean burn mode during middle range operation. During low speed/low load operation, an engine is operated at a preset air/fuel ratio. The engine then transitions to a lean burn mode and operates in the lean burn mode during mid speed/mid load operation. The engine then receives a richer air/fuel ratio during high speed/high load operation.

Abstract: A marine engine has an air intake device that includes an air regulator (e.g., a throttle valve) and fuel injectors. A control system controls an actuator of the air regulator. A first sensor detects an intake pressure in the intake device. A second sensor detects a state of the actuator. A third sensor detects an engine speed of the engine. A control device controls an amount of fuel sprayed by the fuel injectors relative to an amount of the intake air. The control device controls the amount of the fuel based upon a signal of the third sensor and a signal of the first sensor in a first actuation range of the actuator in which the intake pressure is variable. The control device controls the amount of the fuel based upon a signal of the third sensor and a signal of the second sensor in a second actuation range of the actuator in which the intake pressure is invariable.

Abstract: A marine engine has an air intake device that includes an air regulator (e.g., a throttle valve) and fuel injectors. A control system controls an actuator of the air regulator. A first sensor detects an intake pressure in the intake device. A second sensor detects a state of the actuator. A third sensor detects an engine speed of the engine. A control device controls an amount of fuel sprayed by the fuel injectors relative to an amount of the intake air. The control device controls the amount of the fuel based upon a signal of the third sensor and a signal of the first sensor in a first actuation range of the actuator in which the intake pressure is variable. The control device controls the amount of the fuel based upon a signal of the third sensor and a signal of the second sensor in a second actuation range of the actuator in which the intake pressure is invariable.

Abstract: A marine engine is controlled to operate in a lean burn mode during middle range operation. During low speed/low load operation, an engine is operated at a preset air/fuel ratio. The engine then transitions to a lean burn mode and operates in the lean bum mode during mid speed/mid load operation. The engine then receives a richer air/fuel ratio during high speed/high load operation.

Abstract: A number of embodiments of outboard motors employing direct fuel injection systems having high pressure fuel pumps that are mechanically driven off of the engine crankshaft. A wide variety of driving arrangements are disclosed which include direct and indirect drives and drive that employs flexible transmitters and other types of driving arrangements. Furthermore, the pump operating mechanisms are also provided with lubricating systems that will permit servicing of the lubricant even though the drive arrangement may be positioned outside of the crankcase of the engine. Furthermore, arrangements for mounting various components including the fuel pump and other engine-driven accessories in an outboard motor are shown.

Abstract: A fuel supply system for providing fuel from a fuel source to a combustion chamber of an engine is disclosed. The fuel supply system includes a vapor separator in which vapor is separated from fuel supplied from the fuel source. A pre-pressurizing pump pressurizes fuel from the vapor separator to a first pressure and delivers it to a high pressure pump. The high pressure pump pressurizes the fuel to a pressure above the first pressure and delivers it to a fuel rail to which is connected a fuel injector for delivering fuel into the combustion chamber. A fuel return line extends from the fuel rail for returning undelivered fuel back to the fuel system. A valve controls the flow of fuel through the return line and maintains the fuel at high pressure in the fuel rail. A fuel cooler is provided along the return fuel line.

Abstract: A fuel injection system for supplying fuel from a fuel source to an internal combustion engine having at least one combustion chamber, the engine preferably powering an outboard motor, is disclosed. The fuel injection system comprises at least one fuel injector for supplying fuel to the combustion chamber of the engine, a pump delivering fuel at high pressure to at least one fuel rail arranged to deliver fuel under high pressure to the at least one fuel injector, a pressure sensor for detecting a pressure of the fuel in the fuel rail, and a valve controlling a by-pass passage through which a portion of the fuel pumped by the pump may be selectively diverted away from the fuel rail, based upon the fuel pressure detected by the pressure sensor.

Abstract: A fuel supply system includes a fuel pump for providing fuel from a fuel source to an electrically operated fuel injector for injection into a combustion chamber of an engine. The fuel pump has a follower driven pumping element. The follower is actuated by a cam element, with movement of the cam element powering the follower, effecting pumping by the pump. The cam element is rotated by a crankshaft of the engine.

Abstract: A fuel supply system for providing fuel from a fuel source to a combustion chamber of an engine is disclosed. The fuel supply system includes a vapor separator in which vapor is separated from fuel supplied from the fuel source. A pre-pressurizing pump pressurizes fuel from the vapor separator to a first pressure and delivers it to a high pressure pump. The high pressure pump pressurizes the fuel to a pressure above the first pressure and delivers it to a fuel injector for delivery into the combustion chamber. Preferably, a fuel cooler is provided between the vapor separator and high pressure pump for cooling the fuel. In addition, a valve is diverts a portion of the fuel supplied by the high pressure pump back to the vapor separator.

Abstract: A fuel injected engine accounts for differences in intake and exhaust path lengths between cylinders of a cylinder bank by adjusting the amount of fuel delivered to each cylinder depending upon the position of the cylinder within the bank and upon the operational condition of the engine. At low load conditions, an electronic control unit of the engine instructs the fuel injectors to inject more fuel into an upper cylinder than into a lower cylinder within the same cylinder bank. At higher load conditions, however, the fuel injectors inject equal amounts of fuel into all cylinders of the cylinder bank. The amount of fuel delivered for a given load condition desirably minimizes hydrocarbon emissions and maximizes produced torque. The engine also includes a muffler with dedicated expansion chambers for each cylinder bank. This arrangement isolates the exhaust systems associated with each cylinder bank from each other.