Method for operating a fuel tank arrangement for a motor vehicle, and corresponding fuel tank arrangement

A method for operating a fuel tank arrangement for a motor vehicle, the fuel tank arrangement having a fuel tank, a hydrocarbon filter and a pump, wherein the fuel tank is fluidically connected via a tank shut-off valve to the hydrocarbon filter and the hydrocarbon filter is fluidically connected, on the one hand, via the pump to an external environment of the fuel tank arrangement and, on the other hand, via a purge valve to an intake tract of an internal combustion engine, wherein a first leakage test mode is carried out when the pressure pre-sent in the fuel tank is greater than a pressure threshold value, in which a shut-off valve arranged in terms of flow between the pump and the external environment is closed and the tank shut-off valve is opened and then, during a test period, the pressure in the fuel tank is measured by a pressure sensor arranged in the fuel tank and, if a differential threshold value is exceeded, a leakage of the fuel tank arrangement is detected by a pressure difference of a pressure drop of the pressure over a specific period of time.

A fuel tank arrangement for a motor vehicle, comprising:

• a fuel tank, a hydrocarbon filter and a pump, the fuel tank being fluidically connected to the hydrocarbon filter via a tank shut-off valve and the hydrocarbon filter being fluidically connected, on the one hand, to an external environment of the fuel tank arrangement via the pump and, on the other hand, to an intake tract of an internal combustion engine via a shut-off valve, wherein the fuel tank arrangement is provided and designed to carry out a first leakage test mode when a pressure present in the fuel tank is greater than a pressure threshold value, in which a shut-off valve arranged in terms of flow between the pump and the external environment is closed and the tank shut-off valve is opened and then, during a test period, the pressure in the fuel tank is measured by a pressure sensor arranged in the fuel tank and, if a differential threshold value is exceeded, a leakage of the fuel tank arrangement is detected by a pressure difference of a pressure drop of the pressure over a specific period of time.

The method according to claim 3, wherein during the monitoring peri-od a gradient of the pressure over time is determined and compared with a gradient threshold value, wherein the pressure is determined when the gradient falls below the gradient threshold value and a switch from the first leakage test mode to the second leakage test mode is carried out when the pressure falls below a minimum pressure.