Patent ID: 7438052

Claim:
A device for determining abnormality of a fuel supply system that supplies fuel in a fuel tank to an accumulator via a fuel pump, and supplies fuel stored under pressure in the accumulator to an internal combustion engine, the fuel supply system including a relief mechanism for returning fuel in the accumulator to the fuel tank, and a fuel pressure sensor for detecting the pressure of the fuel in the accumulator as detected fuel pressure, comprising: inflow fuel amount parameter-detecting means for detecting an inflow fuel amount parameter indicative of an inflow fuel amount of fuel flowing into the accumulator from the fuel tank; outflow fuel amount parameter-detecting means for detecting an outflow fuel amount parameter indicative of an outflow fuel amount of fuel flowing out of the accumulator into the fuel tank; fuel flow rate relationship parameter-calculating means for calculating a fuel flow rate relationship parameter indicative of a relationship between the inflow fuel amount parameter and the outflow fuel amount parameter; normal-time fuel pressure-calculating means for calculating a normal-time fuel pressure indicative of a pressure of fuel in the accumulator which is to be detected when the fuel supply system is normal, according to the calculated fuel flow rate relationship parameter; and abnormality determining means for determining abnormality of the fuel supply system, based on a result of comparison between the detected fuel pressure detected by the fuel pressure sensor and the calculated normal-time fuel pressure.