Abstract: A fuel supply system for use with an engine having four vertically-arranged cylinders and multiple charge formers prevents air or vapor pockets from accumulating within the fuel pump or fuel lines. A pair of fuel pumps are mounted vertically one above the other. A fuel inlet port of each pump is formed at the lower-most portion of the pump. A fuel discharge port is formed at the upper-most portion of each port. A conduit attached to the top fuel pump's discharge port supplies fuel to an uppermost and lowermost carburetor. A conduit from the lowermost fuel pump supplies fuel to the middle two carburetors. The uppermost carburetor's fuel inlet port is positioned vertically higher than the top fuel pump's discharge port. The second carburetor's fuel inlet port is positioned vertically higher than the second fuel pump's discharge port.

Abstract: An improved overheat detection system for an engine having at least one coolant jacket which is drained of coolant when the engine is not running. The coolant jacket has an inlet portion into which the coolant is supplied and an outlet portion from which the coolant is discharged during the engine is running. In one feature of this invention, the overheat detection system has a sensor for sensing a temperature associated with the coolant jacket at an aft part of the coolant jacket including the outlet portion. In another feature of this invention, the overheat detection system has at least two sensors, one is positioned at a fore part of the coolant jacket including the inlet portion and another is positioned downstream of the former sensor, and both sensors for sensing each temperature associated with the coolant jacket. The overheat detection system is arranged to output an overheat signal in the event the temperature sensed by the sensor or at least one of the sensors is above a predetermined temperature.

Abstract: An exhaust system for an outboard motor wherein the exhaust pipe which depends into the expansion chamber formed in the drive shaft housing is provided with a separate cooling jacket. Water from this separate cooling jacket is discharged into the expansion chamber at a point well below the discharge end of the exhaust pipe in a direction away from the exhaust pipe so as to avoid water ingestion into the engine through the exhaust system. A second expansion chamber communicates with an above the water exhaust gas discharge. This second expansion chamber communicates with the first expansion chamber through a restricted path formed in part by a flange of the exhaust pipe.

Abstract: An outboard motor has a fuel injected internal combustion engine operating on either a two-cycle or four-cycle principle. In some embodiments, the engine is directly injected while in others it is indirectly injected. The engine features one of a number of methods for reducing the temperature of injector drivers. The methods include sensing the temperature of the injector drivers and decreasing the engine speed if the temperature exceeds a predetermined temperature. Another method involves sensing the duration of a high-speed, high-load operating condition and slowing the engine speed if the duration exceeds a predetermined time period. Yet another method involves activating a cooling fan if the temperature of the injector drivers exceeds a predetermined temperature and activating a warning device if the temperature does not decrease with the fan operating.

Abstract: An improved shift mechanism for a marine propulsion transmission is provided. The shift mechanism includes a guide that defines a slot that receives a member of a linkage that connects an operator unit with a shift rod. Movement of the shift mechanism is converted into substantially linear motion and a shift position sensor is located at a substantially right angle to that movement. Information from the sensor is transmitted to a control unit and is employed to prevent abrupt starts. The shift position sensor is located on the side of an engine for ease of assembly and maintenance. Movement of the shift mechanism may also cause pivotal movement of the guide and this pivotal movement may be employed to reduce the engine speed and assist shifting.

Abstract: A driveshaft housing for an outboard motor includes an improved construction. The outboard motor comprises a power head containing an engine, the driveshaft housing depending from the power head and containing a driveshaft, and a lower unit depending from the driveshaft housing and supporting a propulsion device. The engine includes an exhaust system having an exhaust conduit at least in part extending through the driveshaft housing. The driveshaft housing has a rib extending from one lateral side wall portion to another lateral wall portion between the driveshaft and the exhaust conduit. The stiffening rib strengthen the rigidity of the lateral side walls of the driveshaft housing, and thereby inhibits inward and outward movement of the lateral side walls, particularly in a region where the walls define a portion of an expansion chamber of the exhaust system within the driveshaft housing.

Abstract: A direct injection system and control methodology for two-cycle crankcase compression engines wherein the injection timing is advanced from those normally utilized to avoid the incomplete combustion that results from the prior art method. The injection timing is advanced so that it occurs while the exhaust port is still open but it is timed in such a way that the injected fuel will not be swept out of the exhaust port before the exhaust port closes and so that the fuel will vaporize adequately to be completely burned. The initiation of injection timing is adjusted in response to in combustion chamber air velocity determined by certain parameters such as engine speed and intake air flow.

Abstract: An outboard motor has an induction system and a fuel supply system. The two systems are linked together to improve responsiveness of the fuel supply system based upon fluctuations in pressure within the induction system. The motor includes an induction air pressure detection system. The detection system comprises a pressure sensor and a connection to at least two different air intake pipes of the induction system. The connection between the sensor and the two pipes is configured such that the distance between the sensor and each of the pipes is the same. The detection system is configured to sample the pressure in multiple intake pipes associated with multiple cylinders using connecting conduits that have the same length from each intake pipe to the pressure sensor.

Abstract: A blow-by gas ventilation system for a crankcase of an engine includes an improved construction for distributing blow-by gases more evenly between multiple cylinders. The engine has an air intake device that includes a plurality of air delivery conduits for the cylinders and a plenum chamber housing disposed upstream of the air delivery conduits. The ventilation system comprises a blow-by gas conduit that couples the crankcase with the plenum chamber housing. The plenum chamber housing includes an opening to which the blow-by gas conduit is connected. A baffle is disposed in front of the opening within the plenum chamber housing so as to divide the blow-by gases equally for the respective cylinders.

Abstract: A fuel filter for an internal combustion engine suitable for detecting water accumulated therein. The fuel filter has a holder that is mounted on the engine and holds a filter body. A vessel is detachably affixed to the holder. There is a space between the end of the filter body and the bottom of the vessel. An inlet and outlet are provided for inducing fuel into and discharging it from the vessel. The inlet and outlet are connected relative to each other through the filter body for admitting flow of the fuel. In one feature of this invention, a water detection mechanism is placed under the filter body in the vessel. In another feature of this invention, the vessel is made of a transparent material. In a further feature, the holder is mounted on the engine via a damping member.

Abstract: The present invention is an ignition control system controlling ignition firing timing of an ignition element associated with an engine having an output shaft powering a water propulsion device, an intake system including a throttle valve, and a sensor providing an output signal corresponding to each revolution of the output shaft. The ignition control system calculates a base ignition firing timing from a time between successive previous output signals, determines if a condition of engine acceleration or deceleration exists from a rate of change in the throttle valve position and modifies the basic ignition firing timing based on a condition of engine acceleration or deceleration.

Abstract: A number of embodiments of direct injected V-type outboard motors provided with a very effective fuel supply system wherein the number of components can be significantly reduced as well as the elimination of many of the flexible conduits normally employed. This also permits the fuel system to be assembled as a relatively unitary assembly that can be then affixed to the engine. The arrangement is such that purging of the system from vapors during shutdowns is easily accomplished and the system can be purged without complicated construction. Furthermore, the system can be pressure tested by an arrangement where the low pressure system can bypass the high pressure system when the engine is not operating so as to be pressurized for testing purposes.

Abstract: An improved control mechanism for a marine transmission that provides an effective shift control by forming a crank arm at the lower end of the shift rod which lies below a cylindrical bearing portion. These parts are passed through a key hole shaped opening in the lower unit so that when fully assembled, the bearing portion of the shift rod will be journaled in the cylindrical portion of the key hole shaped slot so as to provide a good bearing arrangement.

Abstract: An engine control for an internal combustion engine is disclosed. The engine preferably includes at least two cylinders or combustion chambers. The engine control is arranged to run the engine in a first mode in which all cylinders are operating and a second mode in which at least one of the cylinders is disabled, such as by misfiring the ignition element corresponding thereto. The engine control is arranged to operate the engine in the second mode only when a predetermined condition, such as idle, is detected for a predetermined amount of time. The engine control is also arranged to prevent the operation of the engine in the second mode if an engine operating condition has changed states, even if the predetermined condition is detected.

Abstract: An improved fuel injection control for direct injected, multiple cylinder, internal combustion engines. The injection control is done by a feed back control device based upon an air fuel ratio sensor. The primary feature of this invention is that the respective injection timing for cylinders are shifted relative to each other so that at least one of the state of emissions contained in the burnt charge and the state of fuel efficiency is almost the optimal every cylinder. In one embodiment, the respective injection timings are controlled to be at the timing where emissions are almost the minimum at each cylinder. In another embodiment, one of the injection timings associated with the cylinder that has the air fuel ratio sensor is advanced than the timing where emissions are almost the minimum.

Abstract: A number of embodiments of outboard motor that are comprised of a power head consisting of a multi-cylinder internal combustion engine and a surrounding protective cowling. Each embodiment also includes a drive shaft housing and lower unit, the latter of which contains a propulsion device for propelling an associated watercraft. The engines are mounted within the protective cowling so their crankshafts rotate about vertically extending axes. In each case the crankshaft is coupled to a drive shaft that depends into the drive shaft housing and lower unit for driving the propulsion device. A flywheel is affixed to the upper end of the crankshaft. A first accessory drive is affixed to the crankshaft below the flywheel for driving at least one engine accessory. The engine accessory is mounted at an upper end of the engine and at least in part within the outer peripheral surface of the flywheel in top plan view.

Abstract: An improved fuel supply system for a direct injected engine accommodated in outboard motors includes a pump drive mechanism, instead of a camshaft, for driving a high pressure fuel pump. A pair of the high pressure fuel pumps is applied in one embodiment and a single one is applied in another embodiment. A pulsation damper is further provided for smoothing output of the fuel pump. The pump drive mechanism is unified with a fuel supply conduit, which has a plurality of fuel injectors, for increasing rigidity of components and affixed to the cylinder body of the engine. Openings on the cylinder head of the engine for accommodating the fuel injectors are larger than the injectors so that accumulated tolerances are absorbed by the gap made between the opening and the injector.

Abstract: A tilt and trim unit for a marine drive eases manual trim or tilt up of the drive, while presenting a compact construction. The unit includes a cylinder having upper and lower fluid chambers. A bypass arrangement selectively bypasses a shock absorbing mechanism of the tilt and trim unit. The bypass arrangement is formed by a sub-chamber and a valve positioned in series on one side of the fluid chambers. This arrangement produces a compact construction. The valve also desirably establishes three operating states for the tilt and trim unit. In one state, the valve is open and the tilt and trim unit is easily moved. In another state, the valve is closed to prevent movement of the tilt and trim unit. In a third state, the valve operates as a one-way valve permitting extension of the tilt and trim unit to raise the marine drive, but inhibiting retraction of the tilt and trim unit.

Abstract: A watercraft engine includes a lubrication system alarm control system which initiates an alarm when lubricant pressure within the lubrication system falls below an acceptable pressure. The alarm system compares lubricant pressure during engine operation with a lower pressure threshold which is determined as a function of engine speed. Thus, partial reductions in lubricant pressure are identified. Additionally, the alarm control system may be configured to emit an alarm if lubricant pressure fluctuates at a rate that is greater than a predetermined pressure fluctuation rate threshold.

Abstract: An outboard motor mounting arrangement wherein the swivel bracket and clamping brackets have interengaging sliding surfaces that take side thrusts and minimize loading on the tilt pin during trim operation. In addition, certain electrical cables and hydraulic conduits are juxtaposed to the steering shaft and mounted so that they pass through the various brackets in a location close to the various pivotal axes to minimize flexure and reduce the necessary length therefor.