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