Abstract: A simply-structured trim sensor measures the trim position of an outboard motor. The sensor operates between a pivot pin, which is fixed to a clamping bracket, and a swivel bracket, which rotates about the pivot pin. The sensor is arranged between the clamping and swivel brackets in a position which allows ready access to the sensor. A technician therefore can easily adjustment or repair the sensor without disassembling any portion of the clamping and swivel brackets, and without moving the outboard motor.

Abstract: Two embodiments of two-cycle V-type crankcase compression internal combustion engines for powering a jet propelled watercraft. In each embodiment, the pistons of the cylinder banks each drive their own crankshafts which are geared by a transmission to an output shaft. The exhaust system for the engine is disposed on the outside of the cylinder banks and includes an expansion chamber and a portion of the exhaust system that passes over the engine. The induction system for the engine is positioned in the valley between the cylinder banks.

Abstract: A mounting arrangement for an outboard motor having a body which is connected to a watercraft mounting bracket by at least one mount is disclosed. The mount includes a resilient isolating member having a spring constant in a direction parallel to an axis extending from the front to the rear of the motor which is greater than its spring constant in direction parallel to a second line extending transverse to the first line. So arranged, the frequency of the excitation force applied to the isolating member over normal engine operating speeds does not correspond to the natural frequency of the isolating member in either direction, and resonant modes are avoided.

Abstract: A shifting mechanism for an outboard drive of a watercraft provides reduced coupling shock when the forward gears are engaged by a dual clutch assembly, as well as provides for consistent and quick engagement of the clutch assembly with the gear. The shifting mechanism involves a first gear and a corresponding first clutch, and a second gear and a corresponding second clutch. A plunger carries the first and second clutches which are arranged on the plunger at unequal distances from their respective gears. This nonuniform spacial relationship between the clutches and gears causes one clutch to engage its corresponding gear before the other clutch engages its corresponding gear. The staggered engagement decreases shock on the transmission and permits quicker engagement between the clutches and gears.

Abstract: A number of embodiments of feedback control systems for two-cycle, internal combustion engine management systems. Each embodiment employs an exhaust system sensor which senses the exhaust gases by drawing exhaust gases from the exhaust of the engine. In some instances this is done directly from the cylinder and in others it is done in the exhaust system. In each embodiment, the sensor is provided in an accumulator chamber so as to provide an accurate signal of instantaneous engine running conditions. The use of the accumulator chamber insures that the combustible gases will not be diluted with fresh air charge, but will be able to purge from cycle to cycle so as to provide cycle-by-cycle information. Various arrangements are provided for protecting the sensor element including serpentine flow paths, shields, the direction in which the exhaust gases are delivered, lubricant catalysts, conduit shape, sensor cooling and combinations of these features.

Abstract: An improved feedback control system and method for internal combustion engines that permits extremely accurate feedback control. This is done by utilizing a sensor device that is interrelated with the combustion chambers of the engine so that it only samples the gases from the engine at a time after the exhaust port has opened and before any fresh air charge enters the combustion chamber. By doing this, it is possible to ensure that only combustion product reach the sensor and the sensor chamber will have a time to purge itself of the combustion products from one cylinder before another sampling takes place. This is described in conjunction with both two and four-cycle engines.

Abstract: An outboard motor powered by an engine positioned within a cowling is disclosed. The engine has a block with a cylinder head attached at one side, the block and cylinder head defining vertically arranged combustion chambers. Air intake runners extend from an intake plenum along one side of the engine to intake passages leading through the cylinder head to the combustion chambers. An exhaust system including an exhaust manifold extending from exhaust passages leading through the cylinder head from the combustion chambers is positioned on the side of the engine opposite the runners. A fuel pump is also positioned on the side of the engine with the exhaust system, and an alternator is positioned between the fuel pump and the exhaust system. The runners are separated in the vertical direction, with an oil filter or one or more other engine components positioned therebetween.

Abstract: An outboard motor having a powerhead with a powerhead with a compact internal combustion engine induction system and fuel supply system. The induction system includes a plenum chamber or surge tank that is formed as a housing on an end of the engine opposite to that where the engine induction passage serving the combustion chamber is formed. This common housing also forms passages for carrying fuel between the supply system and the fuel injector including a vapor separator formed integrally in said, housing.

Abstract: An engine choke actuation system automatically controls both the opening degree of the choke and throttle valves of a plurality of charge formers during all phases of engine warmup. The engine choke actuation system also includes a manual override mechanism which allows the associated choke valves to be opened manually in case of a system malfunction.

Abstract: In accordance with the present invention there is provided an outboard motor for use in powering a watercraft of the type having an operator station positioned along a starboard side of the watercraft. The motor has a water propulsion device powered by an engine having an exhaust system generally positioned along a right side thereof. A cooling system is provided for cooling the engine and the exhaust system. Preferably, the motor includes a cooling water tell-tale acting as a visual identifier to the operator of the craft that the cooling system for the engine is operating. The tell-tale is created by diverting coolant from a portion of the cooling system for cooling the exhaust system to a pilot port in the side of the cowling corresponding to the starboard side of the watercraft. In addition, the motor preferably includes a throttle control and shift control which extend along the right side of the engine through the cowling to the operator station in the watercraft.

Abstract: A fuel injection system for an internal combustion engine and particularly an outboard motor. The system includes a fuel vapor separator that is disposed on one side of the throttle bodies at the front of the engine. The fuel vapor separator is comprised of a housing assembly having a cover plate in which an integral fuel inlet fitting, an integral fuel outlet fitting, an integral vent fitting and an integral fuel return fitting are formed. The fuel injectors for the engine are disposed on the opposite side of the throttle bodies from the fuel vapor separator and are supplied with fuel through a vertically extending fuel rail. The pressure regulator is positioned at the top of the fuel rail and the fuel rail is directly affixed to the throttle bodies.

Abstract: A lower unit for an outboard drive has an elongated length in order to present a streamline shape while providing sufficient width to house a transmission for a counter-rotational propeller system with a forwardly-oriented clutch element. One of the clutch elements of the transmission lies in front of the transmission gears to increase the flow area through an exhaust discharge path behind the transmission. In order to accommodate this transmission structure, the lower unit has an increased with at a point forward of the associated drive shaft. The lower unit also has an increased length as measured from the drive shaft forward in order to present a streamline shape within the water. The elongated length of the lower unit also improves the directional and rolling stability of the outboard drive.

Abstract: A fuel injection system for an internal combustion engine provides a uniform flow of gaseous and liquid fuel to each of the intake passages of the engine. A balance passage interconnects each of the intake manifolds to each other and balances the pressure within the intake passages. A pressure regulator regulates the fuel pressure at the fuel injector. A reference pressure chamber within the pressure regulator communicates with the balance passage and controls the fuel pressure based on the balanced pressure within intake passages. The balance passage also communicates with a vapor separator of the fuel supply system that separates liquid fuel from gaseous fuel. The balance passage promotes even distribution of the gaseous fuel to the intake passages. The fuel injection system also includes plenum chamber that acts a source of air for the engine. The plenum chamber includes an drain outlet that communicates with the balance passage for returning blown back fuel from the plenum chamber to the intake passages.

Abstract: A number of embodiments of engine control systems wherein fuel injection and spark timing is controlled by individual sensors associated with each of the combustion chambers. This provides more accurate fuel-air control and ignition control, particularly when operating at low speeds when the angular rotational speed of the crankshaft may vary significantly during a single revolution. However, the system includes a fail-safe mode that will provide continued operation in the event an output is not received from one or more sensors. In this event, the timing of the fuel injection and/or ignition is controlled by the output from another sensor. The timing may be done simultaneously from that other sensor output, or in a timed interval after that other sensor output.

Abstract: An outboard motor embodying a four-cycle internal combustion engine having a decompression device for automatically reducing the compression ratio to assist in pull starting. The decompression device is mounted and operated through one end of the cam shaft and thus facilitates modification of engines so as to incorporate this feature or not incorporate the feature. The construction also facilitates lubrication of a centrifugal mechanism that actuates the decompression device.

Abstract: A system for flushing the cooling system of the engine in a watercraft is provided, whereby a conduit connected to a source of fresh water is inserted into an adaptor located in the upper body of the watercraft. A self-closing valve is attached to the adaptor for sealing the adaptor, and the conduit automatically opens the valve when it is connected to the adaptor, allowing fresh water to flow through the adaptor and into the cooling jacket of the engine.

Abstract: An electrical system for an engine of the type utilized to power an outboard motor is disclosed. The engine has a body with a crankshaft rotating therein. At least one fuel injector supplies fuel to the engine for combustion. The electrical system includes an electronic engine control unit for controlling at least the fuel injector based upon one or more sensed conditions. The electrical system also includes at least one sensor for providing data regarding one or more conditions. Preferably, at least an air pressure and intake air temperature sensor are provided. The sensors are mounted to a portion of the engine body adjacent the crankshaft, preferably via a vibration isolated bracket, for improving sensor accuracy and reliability.

Abstract: A blade design for a counter-rotating propeller system improves the performance of the outboard drive on which is it employed when the propellers are run partially exposed. The propeller system includes a pair of counter-rotating propellers that rotate in opposite directions about a common axis. The rear propeller has a smaller diameter--about 92% of the front propeller--and a total blade face surface area of about 85% of the total blade face surface area of the front propeller. The blades of the front and rear propellers desirably have the same camber and generally the same pitch. The rear propeller pitch is between 90% and 110% of the front propeller pitch. These blade parameters improve the efficiency of the rear propeller over prior designs when the propellers run partially exposed in order to maximize the thrust produced by the propulsion system.

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.

Abstract: A number of embodiments of four-cylinder, four-cycle outboard motors having a compact exhaust system and yet one in which the exhaust pulses from one cylinder are not transmitted to other cylinders so as to interfere with their operation. This is accomplished by providing a series of paired exhaust manifolds with no two successive firing cylinders being served by the same manifold.