Abstract: A number of embodiments of drain-control systems for two-cycle crankcase compression internal combustion engines wherein collected lubricant and condensed fuel may be pumped out of a low spot in the engine when certain engine conditions exist. The pumped liquid is delivered back either to the engine through its induction system or exhaust system for further burning or is mixed with the fuel that is delivered to the engine. Adjustments are made in the fuel-air ratio supplied by the charge-forming system when the drains are being pumped so as to avoid uneven running.

Abstract: A two cycle crankcase compression fuel injected internal combustion engine has a first set of one or more throttle valves (104, 106) controlling combustion air flowing into the crankcase, and a second set of one or more throttle valves (110, 112) also controlling combustion air flowing into the crankcase. A throttle position sensor (104, 106) and controls fuel injection according to throttle position. Increased resolution of sensed throttle position at low engine speed is provided by admitting combustion air only through the first set of throttle valves (104, 106) and not through the second set of throttle valves (110, 112) at low engine speed for an initial given range of motion, such that greater movement of the first set of throttle valves (104, 106) is required to obtain a given amount of combustion air flow for a given engine speed, prior to opening the second set of throttle valves (110, 112), to provide more accurate fuel injection and better driveability.

Abstract: The idle exhaust pressure relief system in an outboard motor is utilized to simultaneously heat the engine crankcase or other parts of the fuel supply system to prevent the puddling of fuel typically occurring at lower engine temperatures. Because the idle exhaust pressure relief system is inherently operable to conduct hot exhaust gases out of the exhaust manifold only at idle or low speed operation, heat is supplied to the crankcase only at temperatures when fuel puddling typically occurs.

Abstract: A marine fuel injection system for a two cycle crankcase compression internal combustion engine includes a puddled fuel return line (44) between the crankcase (16) and a vapor separator (33). A shut-off valve (50) in the puddled fuel return line (44) is closed at high engine speed to prevent the flow at a high rate of a substantially gaseous medium to the vapor separator, to prevent fuel foaming otherwise caused thereby in the vapor separator and which would pass through the vapor vent line (41) to the induction manifold (17), causing an over-rich condition at high engine speed. At low engine speed, the shut-off valve (50) is open, permitting flow of puddled fuel to the vapor separator, which flow is substantially more liquidic and at a lower rate.

Abstract: A marine fuel injection system for a two cycle crankcase compression internal combustion engine includes a puddled fuel return line (44) having an outlet (44b) in the excess fuel return line (43) from the fuel injector (24) and pressure regulator (26) to the vapor separator (33) and high pressure fuel pump (25) for recirculation. Excess fuel return flow creates a vacuum at the outlet (44b) of the puddled fuel return line (44) to suction puddled fuel therethrough for recirculation together with the excess fuel to the fuel pump (25). The end (44d) of the puddled fuel return line (44) at the outlet (44b) extends within and parallel to the excess fuel return line (43) to occupy a portion of the cross sectional area of the latter to reduce such cross-sectional area and create a venturi in the excess fuel return line (43) at the outlet (44b) of the puddled fuel return line (44).

Abstract: An outboard motor powered by a two-cycle crankcase compression internal combustion engine. A system is incorporated for draining condensed fuel from a plurality of locations in the engine induction system through a common conduit to a combustion chamber for combustion.