Please post the Type and Code, as well as the Model, so we can be sure we are all talking about the same engine. Have you checked the carburetor mounting flange gasket? You probably have either a fairly severe intake leak, or a carburetor malfunction, so we need to go through an investigation process. Meanwhile, please do not put petrol into the carburetor intake of a running engine - it is extremely dangerous. The correct way to make the test is to put a small spoonful into the cylinder through the spark plug hole.
