Abstract: A diagnostic system is provided for a watercraft that is propelled by an outboard drive. Sensors can detect conditions of components related to at least the operation of the outboard drive. The diagnostic system can leave inside and outside computers. The inside computer is placed in the watercraft, while the outside computer is placed out of the watercraft. The outside computer is installed with a program to provide the inside computer with an instruction signal to start a diagnosis on the components. The inside computer is installed with a program to provide sensors with a commencement signal to start checking the components, to require the sensors to provide a detection signal, to collect detection signals, and to provide the outside computer with a result of the checking based upon the detection signals. The program of the outside computer additionally controls a monitor of the outside computer to indicate the conditions of the components based upon the result of the checking.

Abstract: An engine of an outboard motor includes a fuel injection system that is configured to increase the accuracy of fuel pressure measurements and more precisely control the amount of fuel injected. In a preferred mode, the fuel injection system can include a pressure dampening device that is connected to the direct fuel injected system. The system can also include a vibration dampening apparatus that protects a pressure sensor from damage that can be caused by engine vibrations.

Abstract: A watercraft is equipped with an outboard motor and an inboard local area network (LAN) that communicates control signals to the outboard motor. An outboard motor operating device retains the ability to operate the outboard motor even if part of the inboard LAN develops an abnormality. In particular, a control signal that controls the outboard motor and a conditional information signal that indicates a condition of the watercraft are transmitted by independent cables that are mutually separated. Even if the cable for transmitting the conditional information signal or equipment connected to the cable develops an abnormality, transmission of the control signal for controlling the outboard motor is not hindered since the control signal is on the other cable, which is not affected by the abnormality. The conditional information signals are processed to generate and display return-to-port warnings based on the watercraft conditions and other operator issued constraints.

Abstract: An internal comustion engine has an air induction system that provides an intake passage and an intake silencer, wherein there are a plurality of openings between the silencer and the intake passage. The openings can be selectively closed so as to effectively lengthen or shorten the flow path through the intake passage. upstream portions of the intake passage are disposed within the intake silencer so as to facilitate compactness of the induction system. The openings are closed during low and medium engine speeds, and are opened during high engine speeds.

Abstract: A marine drive has an open loop cooling system for cooling various engine components using water drawn from the body of water in which an associated watercraft is operating. A water inlet of the cooling system has a filter cover which includes a series of apertures through which water can flow. The apertures have a maximum cross-sectional width. After passing through the water inlet, cooling water is pressurized and directed to an engine coolant passage to cool engine components. A pilot water passage branches off of the engine coolant passage and delivers cooling water through peripheral engine components to cool the components. The pilot cooling water is discharged from the marine drive in a pilot water stream that is visible to the operator of the watercraft. No portion of the pilot water passage has a diameter that is less than the maximum dimension of the water inlet filter cover openings.

Abstract: A cowling assembly for an outboard motor includes an improved construction that can supply relatively cool air containing little water to the induction device and can also supply air to cool engine components without reducing the charging efficiency. The outboard motor has an engine that includes an air induction device and is enclosed within the cowling. The cowling assembly defines a closed cavity in which the engine is contained and has an air intake system. An air intake duct structure introduces air into the cavity. The intake duct structure includes a plurality of relatively narrow connection passages and has an expansion chamber portion disposed on the downstream side of the passages. Intake noise is reduced by this construction. In one preferred form, the cowling assembly additionally has a second intake system. One or more connection passages communicate with the first air intake system and the second air intake system.

Abstract: A lubrication system for a direct injected V-type two-cycle engine is disclosed having a lubricant pump adapted to discharge lubricant into each crankcase chamber of the engine through ports positioned adjacent the downstream side of reed valves of the air intake system. Ports supplying lubricant to cylinders in the right cylinder bank of the engine extend through a left wall of the corresponding crankcase chamber. Ports supplying lubricant to cylinders in the left cylinder bank of the engine extend through a right wall of the corresponding crankcase chamber. During engine assembly, the lubricant pump is manually driven before it is mechanically installed so as to fill the attached supply hoses with lubricant. The pump delivers lubricant to each crankcase chamber at a rate high enough to avoid lubricant carbonization at engine idle and low enough to avoid lubricant resistance to crankshaft rotation, which may make the engine difficult to start.

Abstract: A marine drive includes an oil pump assembly circumferentially mounted on a rotating shaft. The pump assembly defines a pump chamber. An upper seal member is provided above the pump chamber to effectuate a seal with the shaft so that foreign matter will be inhibited from passing downwardly past the upper seal. An intermediate seal member is provided below the pump chamber and also effectuates a seal with the shaft. The intermediate seal member minimizes leakage of oil from the chamber downwardly past the intermediate seal, and is more specifically directed to inhibit invasion of foreign matter, such as water, upwardly past the seal member. A lower seal member is provided below the intermediate seal member and also effectuates a seal with the shaft. The lower seal member acts as another barrier to inhibit leakage of oil downwardly past the lower seal and invasion of foreign matter upwardly past the lower seal.

Abstract: An outboard motor includes a cowling substantially enclosing an engine therein. The engine has an air induction device for introducing air to a combustion chamber, and an exhaust system for communicating exhaust products away from the combustion chamber. The air induction device has an intake opening near a front end of the engine. The cowling has an air inlet at a rear portion of the cowling. An air guide member is disposed between the cowling air inlet and an engine cover, which is positioned atop the engine. The air guide member and engine cover cooperate to direct air toward a rear and center of the engine.

Abstract: An outboard motor includes a cowling substantially enclosing an engine therein. A tilt and trim mechanism includes a manually-actuable tilt switch for controlling tilt and trim of the motor. Both the port and starboard sidewalls of the cowling have apertures formed therethrough. The apertures are sized and configured to accomodate a tilt switch. In one embodiment, a tilt switch is arranged in one aperture and a plug is arranged in the other aperture. In another embodiment, tilt switches are arranged in both apertures.

Abstract: A number of embodiments of personal watercraft having catalytic exhaust systems for treating and purifying the exhaust gases. In all of the embodiments, the catalyst is positioned and disposed so as to be protected from water. In addition, arrangements are provided for cooling the catalyst, for circulating ventilating air across it, for isolating it from other components such as the fuel tank, and for permitting its flushing with fresh water after operating in a salt water environment.

Abstract: An outboard motor includes a housing unit adapted to be mounted on an associated watercraft. An engine is mounted on the housing unit. The housing unit defines a water delivery passage and a water discharge passage. Both the passages communicate with each other through a lower opening. The water delivery passage is arranged to deliver cooling water to the engine. The water discharge passage is arranged to discharge the cooling water from the engine. The discharge passage communicates with a location out of the housing unit through an upper opening. A pressure relief valve unit extends through the lower and upper openings. The pressure relief valve unit allows the cooling water in the delivery passage to move to the discharge passage when a pressure of the delivery passage becomes greater than a preset pressure.

Abstract: An engine includes an air induction system, a fuel supply system, a lubrication system and a ventilation system. The fuel supply system has a fuel reservoir in which a space for fuel vapors is defined. The lubrication system lubricates a component of the engine with lubricant. The ventilation system couples a crankcase of the engine with the air induction system so as to deliver oil vapors in the crankcase to the air induction system. A fuel vapor passage is arranged to couple the space of the fuel reservoir with the ventilation system.

Abstract: A small watercraft includes an engine and an improved induction and charging forming system. The engine includes a fuel injection system with at least one fuel injector and a fuel delivery conduit for supplying fuel to the at least one fuel injector. The induction system includes an intake box configured to protect the at least one fuel injector and the fuel delivery conduit from damage that can be caused by heat generated from a portion of an exhaust system and/or water that may collect in a hull of the watercraft. The induction system can also include a set of throttle bodies. Each throttle body includes a throttle valve. The throttle valves are connected to a throttle shaft assembly. A pulley is attached to the throttle shaft assembly and is disposed between adjacent throttle bodies.

Abstract: An engine throttle valve linkage includes an improved construction that can be placed in a space around an engine in an internal cavity of a protective cowling so as to control throttle valves under a synchronized condition. In a preferred mode, the engine includes first and second air intake conduits communicating with combustion chambers in the respective cylinder banks of the V-shaped engine and extending generally along side surfaces of the engine body. The first and second intake conduits have first and second throttle valves, respectively, both regulating an amount of air flowing through the respective intake conduits. A manipulator actuates both the first and second throttle valves. The manipulator includes a pair of manipulating members coupled with the first and second throttle valves. The manipulator is disposed generally between the first and second air intake conduits so as to be positioned on the engine body.

Abstract: A power transmission system for a marine propulsion unit includes an improved construction that can absorb a shock generated when a shift mechanism is operated. The propulsion unit has a powering element and a propulsion device. The power transmission system includes a first shaft driven by the powering element and a second shaft driven by the first shaft and driving the propulsion device. The first and second shafts have a common axis. A coupling assembly is mounted on both the first and second shafts so as to couple them for rotation together. A damper is disposed next to the coupling assembly. The coupling assembly includes a pair of coupling members. One of the coupling members is axially moveable along the common axis relative to the other coupling member to compress the damper at the moment the first shaft is rotated relative to the second shaft. In another arrangement, a lost motion mechanism operates when the first shaft is rotated relative to the second shaft such that the initial shock is damped.

Abstract: An engine includes an engine body and an air induction system. The engine body includes a cylinder block defining a cylinder bore in which a piston reciprocates. A cylinder head member closes an end of the cylinder bore to define a combustion chamber together with the cylinder bore and the piston. The air induction system is arranged to introduce air into the combustion chamber. The induction system includes a first intake conduit through which the air flows to the combustion chamber. A first plenum chamber unit is disposed upstream of the first intake conduit. A control mechanism is arranged to control an amount of the air flowing through the first intake conduit. The induction system also includes a second intake conduit through which the air flows to the combustion chamber. A second plenum chamber unit is disposed upstream of the second intake conduit. The second intake conduit is coupled with the first intake conduit downstream of the control mechanism.

Abstract: A marine drive comprises an engine having a cooling system adapted to cool the combustion chambers, air intake system, and the power generator. Intake coolant passages are formed on either side of the crankcase so as to lie adjacent reed valves that are positioned within the crankcase. Cooling water is directed through the intake cooling jackets in order to dissipate heat that may accumulate in the intake valves. Another cooling jacket is defined adjacent a portion of a flywheel magneto generator assembly. Cooling water is directed through this generator cooling jacket to absorb heat generated within the magneto coil of the generator. Accordingly, the magneto coil is protected further from damage that may occur if it is exposed to excessive heat. This arrangement has particular advantages with direct-injected, two-cycle engines in which no lubricant is directed across the intake valves.

Abstract: A lubrication system for an internal combustion engine includes an oil pump assembly driven by the crankshaft. The oil pump can be mounted in various positions for maintaining a low center of gravity of the engine. Optionally, or in addition, the engine can include a bearing disposed between a valvetrain drive gear and an output drive gear.

Abstract: A throttle valve control mechanism for an internal combustion engine. In one feature of the invention, the engine has multiple cylinders extending generally horizontally, spaced vertically relative to each other. The engine also has an air induction system extending generally horizontally. The air induction system includes a plurality of air intake ducts each having a throttle valve. Each throttle valve has a throttle valve shaft extending generally vertically and linked together. A throttle valve control mechanism is provided. The throttle valve control mechanism has a throttle lever for rotating the throttle valve and the throttle lever is movable in a plane existing generally horizontally. Almost of the other part of the throttle valve control mechanism is movable in a plane existing generally vertically. If the engine is mounted on an outboard motor and encircled by a protective cowling, the other part of the throttle valve control mechanism is placed between the engine and the protective cowling.