Fuel injection control arrangement for internal combustion engine with abnormality detection function therein

A control arrangement for an internal combustion engine which comprises a fuel supply system for supplying and injecting a high pressure fuel into the internal combustion engine and including a high pressure fuel pump, an electrically controlled pressure regulator and a fuel pressure sensor which are disposed along a fuel supply line from a fuel tank to a fuel injection valve;

• and an air/fuel ratio control system including means for determining a target air/fuel ratio for the internal combustion engine in response to an operating condition of the internal combustion engine, an air/fuel ratio sensor for detecting air/fuel ratio of the internal combustion engine, and an air/fuel ratio feed back control means for feeding back a control amount determined in relation to a deviation between the determined target air/fuel ratio and the detected air/fuel ratio, and which control arrangement further comprises an abnormality diagnosis means which diagnoses a possible abnormality in said fuel supply system, when the pressure of the pressurized fuel in said fuel supply system detected by said fuel pressure sensor exceeds predetermined upper and lower limits determined by a control duty for said electrically controlled pressure regulator;
• and an abnormal element decision means which decides an abnormal element in said fuel supply system at least an abnormality either in said fuel pressure sensor or in said electrically controlled pressure regulator based on an amount representing an air/fuel ratio status including the actual air/fuel ratio and the air/fuel ratio feed back control amount extracted from said air/fuel ratio control system for the internal combustion engine, when said abnormality diagnosis means diagnoses an abnormality in said fuel supply system.