Patent ID: 7451038

Claim:
A method for detecting the opening of a passive pressure limiting valve ( 10 ) for releasing fuel from a common rail fuel injection system to a fuel tank ( 2 ) of a fuel supply system including a suction throttle ( 6 ), said method comprising the steps of: based on a stationary rail pressure (pER) present under normal operation, detecting a load reduction when the rail pressure (pCR) exceeds a first limit value (GW 1 ), upon recognizing the load reduction, selectively, setting a PWM signal (PWM) for controlling the suction throttle ( 4 ) temporarily to a PWM value which exceeds the PWM value provided during normal operation, and recognizing the opening of the pressure limiting valve ( 10 ) if, as a result, the rail pressure (pCR) exceeds a second limit value (GW 2 ) and further increases.