Abstract: Several embodiments of engine control systems that require a throttle position signal. The throttle position signal is derived from a computation made utilizing information derived from the linkage system that interconnects the throttle and spark timing controls.

Abstract: A number of exhaust systems for watercraft propelled by a propulsion unit contained within a tunnel formed in the underside of the hull. This tunnel has an opening through the side of the hull and exhaust gases are delivered to the tunnel from the engine through an exhaust system having an exhaust opening communicating with the tunnel. Various flow controlling arrangements are provided for controlling the flow through one or all of the openings so as to assist in exhaust silencing without significantly increasing back pressure.

Abstract: An exhaust system for a marine outboard drive emits engine exhaust gases to the atmosphere at a point proximate to the water surface of the body of water in which the outboard drive is operated. An upper cowling of the outboard drive houses an engine. A drive shaft housing depends from the lower tray of the cowling and terminates at an intermediate housing. The intermediate housing connects a lower propulsion unit to the drive shaft housing. The exhaust system communicates with an exhaust manifold of the engine and extends downwardly through the drive shaft housing. An expansion chamber of the exhaust system is formed principally within the intermediate housing, below the drive shaft housing and above the propulsion device supported by the lower propulsion unit. An exhaust vent communicates with the expansion chamber and emits engine exhaust gases at a point behind the outboard drive near the lower end of the drive shaft housing.

Abstract: A fuel injection system for an internal combustion engine utilizing manifold injection with the injector positioned downstream of a flow controlling throttle valve. The throttle valve is provided with a flow passage that intersects the spray axis of the injector to provide good fuel vaporization and distribution even at low speeds.

Abstract: A number of embodiments of engine knock controls wherein knocking is precluded by retarding the spark timing. In order to improve driveability and smooth engine performance, the amount of fuel supplied is also increased when the spark is retarded to avoid a loss of engine power.

Abstract: A fuel system for an outboard motor includes a low-pressure fuel transport subsystem and a high-pressure fuel delivery system. The fuel transport system guides fuel from a fuel tank located in the hull of the watercraft to a fuel tank located with a cowling surrounding the engine. The high-pressure fuel delivery system supplies fuel to a fuel rail that communicates with fuel injectors of the engine's induction system. The induction system communicates with crankcase chambers on a side of the engine opposite of the engine cylinders. The low-pressure fuel transport subsystem is located on a side of the induction system opposite of the high-pressure fuel delivery subsystem. This layout minimizes the flow path length from the fuel tank within the cowling to the fuel rail. It also reduces the girth of the engine and simplifies the arrangement of the fuel hoses of the fuel supply system.

Abstract: A marine propulsion system and particularly an outboard motor wherein the outboard motor is provided with a control for preventing engine damage in response to an abnormal condition by reducing the speed of the engine through disabling certain cylinders. The cylinders disabled are chosen on the vertical position of the cylinder in the engine so as to provide improved running and avoid undesirable results. In addition, the disabling of the cylinders is precluded until the abnormal condition has existed more than a predetermined time period upon initial start-up so as to permit unencumbered normal warm up of the engine.

Abstract: A feedback control system for an internal combustion engine, particularly as utilized in an outboard motor. An oxygen sensor outputs a signal indicative of the fuel-air ratio for controlling the charge-forming system of the engine to maintain the desired fuel-air ratio. A series of filters, each tuned for a different frequency and a different engine speed, are interposed between the sensor and the control for reducing the effect of noise.

Abstract: An engine control system wherein the engine throttle valve is maintained in a substantial partially opened position at idle and the desired idle speed is maintained by controlling the spark advance. A lost motion connection connects the operator engine speed control with the throttle control so that when the operator speed control reaches a pick up position, the lost motion will be taken up and normal throttle opening will occur. This improves transient running. The system includes arrangements for detecting wear or other changes in the operative condition and compensating for it.

Abstract: An exhaust arrangement for an internal combustion engine wherein the timing of the cylinder events is such that the exhaust port of one cylinder opens before the exhaust port of another cylinder closes so as to improve scavenging and performance. In preferred embodiments, the engine is of a 2-cycle type and the exhaust port of the one cylinder also opens before the scavenge port of the other cylinder closes. The principle is also depicted in conjunction with a four cylinder engine.

Abstract: Two embodiments of silencing devices for a marine propulsion unit that include an engine surrounded by a protective cowling and which is adapted to be detachably connected to the hull of the watercraft. The silencing devices include at least one expansion chamber positioned within the hull and connected to the interior of the protective cowling by a duct. The devices are tuned to silence the noises emanating from the engine which include the induction system noises and/or mechanical noises.

Abstract: A cylinder-disabling control system for a multi-cylinder engine provided with an exhaust manifold to which each exhaust port is connected, which control system comprises: an engine performance sensor; an operation mode selector for selecting the cylinder-disabling mode or the all-cylinders-engaged mode; and a disabled-cylinder designator for designating as disabled at least one of the most upstream cylinder and the exhaust pulse-affected downstream cylinder, when the cylinder-disabling mode is selected, thereby improving driving stability at low rpm's.

Abstract: A fuel-injected engine produces improved performance while reducing hydrocarbon emissions through the use of several control sensors. One of the sensors, a throttle sensor, determines an opening degree of the throttle valves of the engine and transmits this information to an electronic control unit. A unique coupling ensures unitary movement of a shaft of the sensor with the throttle valve to precisely measure the opening degree and to minimize mechanical hysteresis in the sensed position of the throttle valve as the valve opens and closes. The electronic control unit in turn adjusts the amount of fuel injected depending upon the opening degree of the throttle valves. The amount of injected fuel also depends upon the atmospheric pressure to which the engine is subject. A high-pressure fuel delivery circuit includes a fuel pressure regulator that regulates the fuel pressure at the fuel injectors of the engine.

Abstract: An internal combustion engine with a fuel-vapor reduction arrangement, including a combustion chamber, an induction system for introducing an air-fuel charge to the combustion chamber, a fuel charge-forming system for supplying a fuel charge to said combustion chamber, an exhaust system for releasing combustion exhaust from the combustion chamber to the atmosphere, and a fuel-supply system for supplying fuel to the fuel charge-forming system. The fuel-supply system including a fuel-vapor separator and a fuel-vapor conduit connecting the fuel-vapor separator to a point of the engine so that fuel vapors are not directly released to the atmosphere and do not interfere with the air-fuel ratio in the engine.

Abstract: A spark advance system for an internal combustion engine having a conventional throttle operated spark advance that provides a spark advance related to load. In addition, an arrangement is provided for using an alternate spark timing during start-up so as to provide optimum spark timing under start-up conditions.

Abstract: A personal watercraft having a compact engine arrangement for driving a propulsion device such as a jet pump positioned to the rear of and on the underside of the watercraft. The engine is disposed so that its cylinder block is at an angle to a vertical plane, with the exhaust manifold being positioned on the underside of the cylinder bank. An expansion chamber device is provided at the rear end of the engine and at a height that is higher than the exhaust ports of the engine and the discharge of the exhaust system so as to provide a trap for precluding flow of water to the engine through the exhaust system. This positioning of the engine places its crankshaft in offset relationship to the drive shaft of the propulsion device, and a two-stage step-down transmission drives the drive shaft from the crankshaft.

Abstract: A fuel induction system for an internal combustion engine which includes a throttle valve that is positioned substantially open under idle and near idle engine running conditions. The system includes means for disabling one or many of the cylinders in order to maintain a low engine rotational speed at idle and near idle and also means for selectively disabling the cylinders in such a manner as to provide the smoothest running engine possible in those instances where one or many of the engine's cylinders are disabled. The number of cylinders disabled also depends on the load driven by the engine.

Abstract: A hydraulic tilt and trim mechanism for a marine outboard drive wherein the trim cylinder is provided with a valve element that is positioned responsive and which defines a fluid lock when the piston is in a trimmed down position for providing hydraulic resistance to further trim-down operations so as to minimize noise and wear. A mechanical stop is also provided within the trim cylinder.

Abstract: A lubricating and drive system for a marine propulsion transmission that is comprised of an upper reversing transmission and a lower final drive transmission. A lubricant pump is driven off an input shaft to the reversing transmission for supplying lubricant for actuating its clutches and also for lubricating its gears. The pickup for the lubricant pump is disposed at a lower position in the final drive gear case so as to maintain a low lubricant level therein when the unit is operating so as to reduce drag.

Abstract: A control switch assembly for utilization with marine propulsion units to be mounted in, for example, the single lever housing of the transmission and throttle control. The switch assembly includes a sealed outer housing providing at least two cavities for containing switches and a hard wire interconnection to an external terminal for connection to a wire harness.