Abstract: A marine propulsion system includes a two cycle water cooled crankcase compression internal combustion engine (52) including a vapor separator (33), a remote fuel tank (60), and a fuel pump (62) in the tank for delivering fuel to the engine in response to crankcase pulse pressure. A combination conduit (64) between the fuel tank and the engine includes a first passage (66) communicating crankcase pulse pressure from the engine to the fuel pump in the tank, a second passage (70) supplying fuel from the pump in the tank to the engine, a third passage (74) returing fuel vapor from the vapor separator at the engine back to the tank, a fourth passage (78) supplying cooling water from the engine towards the tank, and a fifth passage (82) returning water from the fourth passage back to the engine.

Abstract: A fuel enrichment system for a multi-cylinder engine having a manifold balance line to deliver fuel to each of the cylinders as needed includes a valve located adjacent one of the carburetors to supply additional air/fuel mixture to approximately the center of the fuel balance line during the start-up of the engine.

Abstract: An auxiliary fuel supply system is provided for a two cycle internal combustion engine (302). A first fuel line (350) supplies fuel from the fuel pump (338) to a solenoid (352) which is continuously cyclable between ON and OFF states during running of the engine, includig high speed operation where detonation may occur. Fuel then flows through a second fuel line (354) to a restriction orifice metering housing (356), and then to a plurality of third branch fuel lines (358, 384, 386, 388, 390 and 392) for delivery to respective cylinders. The restriction orifices provide a pressure drop from the second fuel line to the plurality of third fuel lines, to provide lower fuel pressure in the third fuel lines, to reduce the chance of leakage at the intake manifold (326), and also to reduce fuel pressure fluctuations in the third fuel lines otherwise due to cycling of the solenoid. Metering housing structure is disclosed.

Abstract: A cold start fuel enrichment circuit for an internal combustion engine includes a thermistor (204) sensing engine temperature, a voltage source (V.sub.DD) continually biasing the thermistor such that the voltage across the thermistor continually varies with engine temperature and provides an output fuel enrichment signal, and a circuit (218, 220) connecting the engine battery (206) through the start switch (208) to the thermistor to additionally bias the thermistor during cranking of the engine. A combination cold start and knock prevention fuel enrichment circuit is also provided.

Abstract: A carburetor for an internal combustion engine which includes a supplemental fuel chamber and fuel injector valve, manually or remotely actuated, to inject a charge of fuel into the fuel induction chamber of an associated engine and provide a continuing fuel supply to the engine, over and above, the normal carburetor system, to allow the engine to reach a warm-up stage and prevent stalling out until such stage is reached where normal carburetion can take over. Automatic refill and vent valves permit fuel recharge of the supplemental fuel chamber to insure readiness of the chamber for starting at all times.