A system and method for injecting fuel into an engine is provided where a low-pressure fuel pump is connected in fluid communication with at least one port fuel injector and a high-pressure fuel pump is connected in fluid communication with at least one direct fuel injector. The port fuel injector is disposed along an intake path of the engine and the direct fuel injector is disposed adjacent a cylinder of the engine. A lost motion lifter selectively couples the high-pressure fuel pump and the engine. A pump deactivation module switches the lost motion lifter to selectively deactivate the high-pressure fuel pump from the engine in response to partial load operation of the engine. The pump deactivation module may additionally switch the port fuel injector to an activated state and the direct fuel injector to a deactivated state.