Patent ID: 8539934

Claim:
An injection abnormality detection method in a common rail fuel injection control system where fuel in a fuel tank is pressurized and pressure-fed to a common rail by a high pressure pump to enable injection of high pressure fuel to an internal combustion engine via fuel injection valves connected to the common rail, a low pressure control electromagnetic valve is disposed on an upstream side of the high pressure pump, rail pressure control is enabled by drive control of the low pressure control electromagnetic valve, and a pressure holding valve is disposed inside a return fuel passage from the fuel injection valves, the injection abnormality detection method comprising determining there is injection abnormality when, in a state where the low pressure control electromagnetic valve is controlled in a closed loop, the difference between a reference fuel through-flow rate in the low pressure control electromagnetic valve determined in response to the operating state of the engine and a fuel through-flow rate of the low pressure control electromagnetic valve decided in closed loop control of the lower pressure control electromagnetic valve is larger than a predetermined threshold value.