Fuel system and method for operating a fuel system

The method involves providing a venting valve (6) in a fuel tank (2). The venting valve is provided for venting the fuel tank over a specific period, during deactivation of internal combustion engine so that internal pressure and temperature of fuel tank is adjusted to predetermined level. The temperature deformation element is made of bimetal element or wax element. An independent claim is included for fuel system for internal combustion engine.