Patent ID: 7389767

Claim:
A method for diagnosis of a fuel volume control valve for setting a fuel volume flow in an internal combustion engine, the method which comprises: providing a fuel system with a pre-feed pump, a high-pressure pump for feeding fuel to a high-pressure accumulator, a fuel control valve for setting a volumetric flow of the fuel fed by the high-pressure pump to the high-pressure accumulator, at least one injector for injecting the fuel into at least one cylinder of the internal combustion engine connected to the high-pressure accumulator, a pressure sensor assigned to the high-pressure accumulator, and a pressure control valve for setting a pressure in the high-pressure accumulator based on a fuel pressure signal from the pressure sensor; in overrun mode of the internal combustion engine, performing a check whether release conditions for executing the diagnosis are fulfilled, the release conditions selected from a group consisting of whether a speed of the internal combustion engine lies above a first predetermined threshold value, whether a speed of the vehicle driven by way of the internal combustion engine lies above a second predetermined threshold value, whether a clutch of the vehicle is engaged, and whether there is not a request from a driver of the vehicle; and if a result of the inquiry is positive, closing the volume control valve for a predetermined period of time; during the period of time, recording values for the fuel pressure by way of the pressure sensor; comparing the values for the fuel pressure with a predetermined threshold value; if the values for the fuel pressure within the time period are below the threshold value sufficiently often, classifying the volume control valve as fault-free; and otherwise classifying the volume control valve as defective.