Patent ID: 7143747

Claim:
A common rail fuel injection system for an internal combustion engine comprising: a high pressure pump for discharging high pressure fuel; a common rail for accumulating the high pressure fuel supplied from the high pressure pump; multiple injectors for injecting the high pressure fuel from the common rail into respective cylinders of the engine; a pressure sensor for detecting common rail fuel pressure of the high pressure fuel accumulated in the common rail; and a control unit for controlling a discharge amount of the high pressure fuel to be discharged from the high pressure pump in order that a detected fuel pressure (PCi) detected by the pressure sensor will coincide with a target fuel pressure (PC 0 ) calculated in accordance with operational conditions of the engine, and for controlling a fuel injection amount to be injected by the injector in order that an injected fuel amount will coincide with a target fuel injection amount calculated in accordance with the operational conditions of the engine, wherein the control unit comprises; a decreased amount presuming means for calculating a presumed decreased amount (PC 1 ) of the common rail fuel pressure, which occurs as a result of the fuel injection by the injectors; a first determination means for directly or indirectly comparing a detected decreased amount (PC 2 ) of the common rail fuel pressure detected by the pressure sensor with the presumed decreased amount (PC 1 ), and for determining whether an abnormal condition is included in the outputs from the pressure sensor.