Abstract: An arrangement for switching a carburetor in an internal combustion engine in a vehicle adapted for alternative operation on liquid or gaseous fuel. The carburetor is of the type where the pressure upstream of a throttle butterfly determines the engine air and fuel supply by the actuation of a piston provided with a metering needle. When using liquid fuel, the piston executes upward and downward movements, a passage leading through the carburetor thereby being constricted to a varying degree, and similarly the needle is caused to be thrust to a varying degree into a nozzle for metering liquid fuel to the engine induction air. This signifies too rapid wear of the metering needle in alternating operation on liquid and gaseous fuel.