Method and apparatus for operating a fuel supply system

The fuel supply system (10) comprises at least one injection valve (26) comprising a solenoid actuator. Furthermore the fuel supply system (10) comprises a high-pressure pump (20) delivering fuel with a given pressure in a fuel line or a manifold (24), the fuel line or the manifold (24) respectively being hydraulically coupled with an outlet of the high-pressure pump (20) and an inlet of the injection valve (26). The method comprises the following steps: The solenoid actuator is activated according to a predetermined activation signal with a given activation period (Ti) for effecting a fluid flow out of an injection nozzle of the injection valve (26). An actuator voltage (U C) is captured at least in a closing phase (T phase) which starts after the activation period (Ti), wherein the actuator voltage (U_C) represents a voltage induced in the solenoid actuator. It is detected if the fuel pressure of the fuel delivered by the high-pressure pump (20) is within a given range depending on the captured actuator voltage (U C) and a first signal is generated depending on the detection result. Additionally or alternatively the fuel pressure of the fuel delivered by the high-pressure pump (20) is determined depending on the captured actuator voltage (U_C) and a second signal is generated depending on the determined fuel pressure.