A method for operating a fuel feed pump, the fuel feed pump having a pump system and an electrically commutated electric motor, the pump system being drivable by the electric motor, includes: detecting fluctuation in circular motion of the pump system over a rotational speed of the pump system to obtain a value of the fluctuation; standardizing the detected value of the fluctuation to obtain a standardized valise; and in a case in which a predefinable limit is exceeded by the standardized value, limiting a gradient of change in the rotational speed of the pump system.

A method for identifying a source of high pressure leakage of a fuel system of an engine comprising determining pressure decay values at a first pressure and at a second pressure and identifying the source of high pressure leakage based on the pressure decay values at each pressure.

A method for identifying a source of high pressure leakage of a fuel system of an engine comprising determining pressure decay values at a first pressure and at a second pressure and identifying the source of high pressure leakage based on the pressure decay values at each pressure.

A method for operating a fuel feed pump, the fuel feed pump having a pump system and an electrically commutated electric motor, the pump system being drivable by the electric motor, includes: detecting fluctuation in circular motion of the pump system over a rotational speed of the pump system to obtain a value of the fluctuation; standardizing the detected value of the fluctuation to obtain a standardized valise; and in a case in which a predefinable limit is exceeded by the standardized value, limiting a gradient of change in the rotational speed of the pump system.

A control apparatus for a vehicle may include an engine, a fuel tank, a feed pump, a pressure sensor, a motor and an electric storage apparatus. The feed pump feeds the fuel to a port injection valve. The pressure sensor detects a fuel pressure that is fed to the port injection valve. The motor performs cranking of the engine at start time of the engine. The control apparatus includes an ECU. The ECU controls the feed pump based on a detection value of the pressure sensor and controls the motor in order to start the engine. The ECU controls the feed pump and the motor such that the electric storage apparatus feeds electric power to the motor in preference to the feed pump, when an electric power that the electric storage apparatus is able to output at the start time of the engine is less than a determination threshold.

In a fuel system of an internal combustion engine, fuel is delivered by a high-pressure pump into a fuel rail. The quantity of the delivered fuel is influenced by a quantity control valve (30) actuated by an electromagnetic actuating device. A limit-value retaining current is ascertained, at which the quantity control valve still remains in its closed state or is just opening.