Abstract: An oil pressure warning system for an outboard motor for detecting and alarming an abnormal oil pressure of an internal combustion a first oil pressure switch which generates an ON signal when the oil pressure is less than or equal to a first predetermined oil pressure, and a second oil pressure switch which generates an ON signal the oil pressure is less than or equal to a second predetermined oil pressure set higher than the first predetermined oil pressure. The abnormality of oil pressure is detected and alarmed based on the ON signal of the switches. The first and second predetermined oil pressures are first and second predetermined oil pressures is determined based on an oil pressure characteristic of a (possible) maximum oil temperature (under which the engine has been warmed up) set relative to the engine speed, thereby ensuring to detect and alarm the abnormality of oil pressure under any engine speed and any oil temperature.

Abstract: An intake manifold 85 having integrally a surge tank 82, a plurality of intake pipes 83a to 83d and a mounting flange 84 is provided at the mounting flange 84 with a plurality of fuel injection valves 94. A subsidiary tank 89 provided therein with a high pressure fuel tank 91 and provided outside thereof with a high pressure filter 93 for temporarily storing a fuel to be supplied to the fuel injection valves 94 is secured to intake pipes 83c, 83d by means of two bolts 106 and secured to a cylinder block 6 by means of two bolts 107. The high pressure fuel tank 91, the high pressure filter 93 and the subsidiary tank 89 are beforehand assembled to the intake manifold 85 to make a subassembly and the subassembly is collectively assembled to an engine to thereby reduce the number of assembling steps.

Abstract: An engine ignition timing control system for outboard motor having a propeller connected to the engine to be rotated and mounted on a boat such that the boat is propelled forward or backward. The engine is equipped with a decompression mechanism and is started by a recoil starter. In the system, at the time of engine starting, the ignition timing is set to a predetermined crank angle until the detected engine speed exceeds a first prescribed engine speed, while it is set to a value obtained by retrieving a table by at least the detected engine speed after the detected engine speed exceeds the first prescribed engine speed. And, the ignition timing is advanced until the detected engine speed is equal to or greater than a second prescribed value and is then returned to the retrieved value. With this, the engine speed can be reliably increased at starting, without need for a throttle opener or air-fuel ratio enrichment, thereby enhancing engine starting performance.

Abstract: An idling speed control system for an outboard motor mounted on a boat and equipped with an internal combustion engine, whose output is connected to a propeller through a clutch, having secondary air supplier that supplies secondary air. In the system, the engine start-state as to whether the engine has been started is determined and the clutch position is detected and based thereon, the desired idling speed and the desired secondary air supply amount is determined through learning control. With this, the system can therefore accurately determine the desired idling speed and the desired secondary air supply amount and achieve steady idling speed even if load changes owing to a change in clutch position or propeller replacement.

Abstract: A structure for fitting a generator stator to an engine is provided which allows generator stators having different shapes to be fitted selectively to a common engine main body. In order to selectively fit a first or second generator stator having different shapes from each other to the outside wall of an engine main body, a plurality of first fitting bosses for bolting the first generator stator and a plurality of second fitting bosses for bolting the second generator stator are provided at different positions on the outside wall.

Abstract: A subsidiary tank 89 provided on a side wall of an engine block on an outboard engine system temporarily stores a fuel supplied from a fuel tank not shown and provided on a hull, and pressurizes the fuel to a high pressure to deliver it to a fuel injection valve 94. An upper space in the subsidiary tank 89 is connected to an inner space of an intake silencer 76 through two air vent pipes L7, L8. Even when a fuel vapor liquefies in the intake silencer 76 at the time of engine suspension, the liquefied fuel is caught at a bottom of the intake silencer 76 having a large volume with no possibility of flowing out.

Abstract: In a power unit such as an outboard motor is provided in which an engine and an auxiliary fuel tank which temporarily stores fuel to be supplied to a fuel injection valve of the engine and to which extra fuel is returned from the injection valve, are housed in an engine room which is defined by a mount case and an engine cover, the upper ends of air vent pipes extend from the auxiliary fuel tank and communicate with an opening portion which opens in an upper outside surface of the engine cover. Fuel vapor occurring in the auxiliary fuel tank, is discharged from the opening portion. Accordingly, the fuel vapor occurring in the auxiliary fuel tank in the power unit is prevented from being sucked into the engine, and the degradation of the exhaust characteristics of the engine can be avoided.

Abstract: A control apparatus for controlling an engine mounted on a watercraft and driving it so as to finely and stably control a low speed of the watercraft. The control apparatus is adapted to compute a target engine speed on the basis of a correction value for the engine speed which is determined by a correction signal generated by a correction signal generator which is manually operable. The control apparatus controls the opening degree of the secondary air valve in accordance with a desired opening computed on the basis of the computed target engine speed.

Abstract: A four-cycle engine for an outboard motor includes an upwardly extending breather chamber which communicates with a projecting portion provided at a lower part of a crankcase and with an induction system via a PCV passage for returning a blow-by gas to intake manifolds. With this arrangement, it becomes possible to remove oil components from the blow-by gas within the PCV passage and hence to return the substantially oil-free blow-by gas to the intake manifolds.

Abstract: An outboard motor includes an engine which is tiltable from a first position to a second position, and a drive mechanism connected to the engine for driving a propeller. When the engine is in the second position, the drive means is tilted upward. An auxiliary fuel tank is connected to the engine for storing fuel returning from a fuel injection valve side of the engine. A high-pressure fuel pump is connected to the engine and the auxiliary fuel tank for pumping fuel from the auxiliary fuel tank to the fuel injection valve side of the engine. A water jacket is connected to the auxiliary fuel tank, for cooling the fuel which is stored in the auxiliary fuel tank. A water pump is driven by the engine to supply water from an external water source to an inlet of the water jacket. A first discharge passage is connected to an outlet of the water jacket. An engine cover is provided, which covers the engine, the fuel pump, and the auxiliary fuel tank.

Abstract: A four-cycle engine including a magnetic detection sensor mounted on a non-magnetic cam shaft pulley which is rotated in operative association with a crank pulley for detecting a plurality of detecting portions formed on the magnetic detection member by coils mounted in the cylinder head. The magnetic detection member is integrally formed with the plurality of detection portions for different uses such that distances from the center of rotation of the cam shaft pulley to the plurality of detection portions are different, and wherein the coils are separately mounted in correspondence to the detection portions. Thus, it is possible not only to take out timing signals for different uses from a single cam shaft pulley, but also to eliminate interference between the discrete coils.

Abstract: A four-cycle engine including a magnetic detection sensor mounted on a non-magnetic cam shaft pulley which is rotated in operative association with a crank pulley for detecting a plurality of detecting portions formed on the magnetic detection member by coils mounted in the cylinder head. The magnetic detection member is integrally formed with the plurality of detection portions for different uses such that distances from the center of rotation of the cam shaft pulley to the plurality of detection portions are different, and wherein the coils are separately mounted in correspondence to the detection portions. Thus, it is possible not only to take out timing signals for different uses from a single cam shaft pulley, but also to eliminate interference between the discrete coils.

Abstract: A multi-cylinder engine structure includes a multi-cylinder engine body having a plurality of cylinders vertically arranged therein. A fuel feed system has a fuel pump connected to a plurality of carburetors disposed in a vertical arrangement sideways of the engine body in independent correspondence to the cylinders. The fuel pump is disposed below a lowermost one of the plurality of carburetors arranged vertically. An outboard engine includes a case tiltably mounted at a stern. A multi-cylinder engine body is contained in the case. A fuel feed system supplies a fuel to a plurality of carburetors disposed in correspondence with the cylinders. A fuel filter is also provided. The fuel pump is disposed below a lowermost one of the plurality of carburetors arranged vertically and above the fuel filter in a tilted-down state of the case.

Abstract: A V-type multi-cylinder 4-cycle engine E accommodated in an engine room in an outboard motor includes a pair of left and right banks. A surge tank is disposed in a space defined between both the banks and connected to two left and right combustion chambers through intake ports. A throttle body is connected to a lower portion of the surge tank and also to an intake silencer mounted in a left space of the engine room through an elbow. A subsidiary tank for supplying a fuel to an injector is disposed symmetrically with the intake silencer in a right space of the engine room. The employment of the above-described layout makes it possible to make an intake device move compact in the 4-cycle engine.

Abstract: A multi-cylinder engine structure includes a multi-cylinder engine body having a plurality of cylinders vertically arranged therein. A fuel feed system has a fuel pump connected to a plurality of carburetors disposed in a vertical arrangement sideways of the engine body in independent correspondence to the cylinders. The fuel pump is disposed below a lowermost one of the plurality of carburetors arranged vertically. An outboard engine including a case tiltably mounted at a stern. A multi-cylinder engine body is contained in the case. A fuel feed system supplies a fuel to a plurality of carburetors disposed in correspondence to the cylinders. A fuel filter is also provided. The fuel pump is disposed below a lowermost one of the plurality of carburetors arranged vertically and above the fuel filter in a tilted-down state of the case.