Fuel pressure control method and system for direct fuel injection engine

A fuel pressure control system for a direct fuel injection engine having, a starter motor for cranking said engine, an ignition key switch for operating said starter motor, a fuel injector connected to a high pressure fuel system for injecting a high pressure fuel into a cylinder of said engine, a fuel tank for storing a fuel, a feed pump for pumping up said fuel from said fuel tank to a low pressure fuel system and for feeding said fuel from said low pressure fuel system to said high pressure fuel system, a high pressure fuel pump for producing a high pressure fuel in said high pressure fuel system and for supplying said high pressure fuel to said fuel injector, a high pressure fuel regulator for regulating the fuel pressure in said high pressure fuel system and for returning said fuel in said high pressure fuel system to said fuel tank, a fuel sensor for detecting the presence of liquid fuel in said high pressure fuel system, and an electronic control unit for controlling said engine, the system which comprises:

• detecting means for detecting said fuel in said high pressure fuel system by said fuel sensor when said ignition key switch is turned on;
• counting means for counting an elapsed time during which said fuel is detected by said fuel sensor when said fuel is detected;
• judging means for judging whether or not said elapsed time reaches a predetermined time;
• prohibiting means for prohibiting energization of said starter motor so as to render said high pressure fuel pump inoperative until said elapsed time reaches said predetermined time when said ignition key switch is turned on;
• opening means for opening said high pressure fuel regulator so as to return said fuel in said high pressure fuel system to said fuel tank until said elapsed time reaches said predetermined time when said ignition key switch is turned on;
• operating means for operating said feed pump so as to return said fuel in said high pressure fuel system to said fuel tank until said elapsed time reaches said predetermined time when said ignition key switch is turned on;
• and
• energizing means for admitting to energize said starter motor so as to render said high pressure fuel pump operative when said elapsed time reaches said predetermined time.

A fuel pressure control system for a direct fuel injection engine having, starter motor for cranking said engine, an ignition key switch for operating said starter motor, a fuel injector connected to a high pressure fuel system for injecting a high pressure fuel into a cylinder of said engine, a fuel tank for storing a fuel, a feed pump for pumping up said fuel from said fuel tank to a low pressure fuel system and for feeding said fuel from said low pressure fuel system to said high pressure fuel system, a high pressure fuel pump for producing a high pressure fuel in said high pressure fuel system and for supplying said high pressure fuel to said fuel injector, a high pressure fuel regulator for regulating the fuel pressure in said high pressure fuel system, a stop valve for returning said fuel in said high pressure fuel system to said fuel tank, a fuel sensor for detecting a presence of liquid fuel in said high pressure fuel system, and an electronic control unit for controlling said engine, the system which comprises:

• detecting means for detecting said fuel in said high pressure fuel system by said fuel sensor when said ignition key switch is turned on;
• counting means for counting an elapsed time during which said fuel is detected by said fuel sensor when said fuel is detected;
• judging means for judging whether or not said elapsed time reaches a predetermined time;
• prohibiting means for prohibiting energization of said starter motor so as to render said high pressure fuel pump inoperative until said elapsed time reaches said predetermined time when said ignition key switch is turned on;
• opening means for opening said stop valve so as to return said fuel in said high pressure fuel system to said fuel tank until said elapsed time reaches said predetermined time when said ignition key switch is turned on;
• operating means for operating said feed pump so as to return said fuel in said high pressure fuel system to said fuel tank until said elapsed time reaches said predetermined time when said ignition key switch is turned on;
• and
• energizing means for permit energization of said starter motor so as to render said high pressure fuel pump operative when said elapsed time reaches said predetermined time.