Abstract: A fuel injector includes an injector body forming an actuator portion. An actuator bore is formed in the actuator portion and is at least partially defined by an inner surface and by an end surface. An actuator disposed in the actuator bore and has an outer surface such that a flow channel can be defined between the inner surface of the actuator bore and the outer surface of the actuator. A cooling flow passage is formed in the injector body, in fluid communication with the actuator bore, and is adapted to supply cooling fluid to the actuator bore. A drain passage is formed in the injector body, in fluid communication with the actuator bore. An internal cooling fluid flow path extends from the cooling flow passage, through the flow channel, and from the flow channel through the drain passage.