A fuel supply system for a reciprocating-piston engine includes a storage tank; a wall of the storage tank defining a first aperture and a second aperture therethrough; a first fuel injector fluidly coupled with the first aperture of the storage tank via a pressure control module and a first fuel injector supply conduit; a pump fluidly coupled with the second aperture of the storage tank; and a second fuel injector fluidly coupled with an outlet port of the pump via a second fuel injector supply conduit. The pressure control module is configured to maintain a pressure in the first fuel injector supply conduit within a pressure range that includes a pressure value that is less than a pressure inside the storage tank. The pump is configured to maintain a pressure inside the second fuel injector supply conduit that is greater than the pressure inside the first fuel injector supply conduit.

Additional approaches for the reduction of particulate emissions in gasoline engines using optimized port+direct injection are described. These embodiments include control of the amount of directly injected fuel so as to avoid a threshold increase in particulates due to piston wetting and reduction of cold start emissions by use of air preheating using variable valve timing.

Methods and systems are provided for adjusting operation of an internal combustion engine configured for dual fuel injection from a single fuel rail. In one example, a method may include directing fuel from a common high pressure fuel rail to one or more of a direct injector and a port injector, wherein each of the direct injector and port injector may be coupled to a cylinder of an engine. The flow of fuel to the direct injector and port injector from the single fuel rail is mediated by a flow selection valve.

A method for controlling an engine in various operating modes and for controlling an engine having dual injectors, may include selecting a number of injectors configured to inject fuel based on an operating mode of the various operating modes, and injecting fuel based on a selection of whether to inject fuel while an intake valve is open, or to inject fuel while the intake valve is closed.

A fuel supply device may include an intake manifold having both ends thereof respectively connected to intake openings of cylinder heads of each of the cylinders in a V-type two-cylinder general-purpose engine, a throttle body connected to a connection portion of the intake manifold, a fuel injection valve disposed in the throttle body and having nozzles for uniformly injecting fuel to inside of the intake port or to an inner wall surface of the intake port of each of the cylinders through the connection portion of the intake manifold, and a throttle valve disposed to the throttle body upstream of the fuel injection valve.

Methods and systems are provided for operating a lift pump of an engine fuel system. In one example, a method may comprise closed loop operating a lift pump of a fuel system based on a difference between a desired fuel rail pressure and an estimated fuel rail pressure, and open loop operating the lift pump to the desired fuel rail pressure in response to a fuel flow rate in a direction of a fuel rail through a check valve positioned between the lift pump and the fuel rail decreasing to a threshold. Thus, outputs from a fuel rail pressure sensor may not be used to adjust lift pump operation when an amount of fuel flowing to the fuel rail decreases to a threshold.

A multi-cylinder internal combustion engine includes: a first fuel injection valve that injects fuel into each cylinder; a second fuel injection valve that injects fuel into an intake passage; and an exhaust recirculation device that causes some of exhaust flowing in an exhaust passage to recirculate into the intake passage. A control device is used in the multi-cylinder internal combustion engine. The control device limits recirculation of exhaust into the intake passage by the exhaust recirculation device when imbalance determination is conducted during engine operation by fuel injection from the first fuel injection valve only, compared to when imbalance determination is conducted during engine operation involving fuel injection from the second fuel injection valve.

A gasoline-diesel complex combustion engine may include a cylinder including a cylinder body in which a combustion chamber is formed to generate a driving power by combusting a gasoline fuel and a diesel fuel and a cylinder head formed to cover an upper portion of the cylinder body, a pair of intake ports formed in the cylinder head, a pair of exhaust ports formed in the cylinder head, a diesel injector disposed in a center of the cylinder head, a pair of spark plugs disposed on opposite sides of the diesel injector, a first intake pipe and a second intake pipe mounted in the intake ports, an exhaust pipe mounted in the exhaust ports, a pair of intake valves disposed in the first and second intake pipes, and a gasoline injector disposed in the first and second intake pipes to inject the gasoline fuel into the combustion chamber.

A two-stroke internal combustion engine has a crankcase, a cylinder block defining at least one cylinder, a cylinder, a crankshaft, at least one piston, at least one scavenge port, at least one throttle body for supplying air to an interior of the crankcase, at least one direct fuel injector fluidly communicating with at least one combustion chamber for injecting fuel directly in the at least one combustion chamber; and at least one port fuel injector fluidly communicating with the interior of the crankcase for injecting fuel upstream of the at least one combustion chamber. Methods for controlling an engine having at least one direct fuel injector and at least one port fuel injector are also described.

Low-cost fuel injection systems for internal combustion engines, including vapor fuel engines are provided.