A low leakage large bore fuel system (10) includes a common rail (16) fluidly connected to at least one of a source of heavy fuel oil (12) and a source of distillate diesel fuel (14). A plurality of fuel injectors (30) are fluidly connected to the common rail (16) and each include a cooling inlet (35) and a cooling outlet (36). Each fuel injector (30) also includes an electrical actuator (40) coupled to a direct operated nozzle check valve by a pilot valve member (41) and a control valve member (45). Fuel leakage is reduced between injection events by equalizing pressures in a pilot control chamber (63) and an intermediate control chamber (62) that are separated by a guide surface of the control valve member (45). Also, between injection events the pilot valve member (41) blocks a drain outlet (37) from a common rail inlet (33) of the fuel injector (30).