A properly working tank vent should only allow air to enter the tank as not to create a vacuum... But should seal off to pressure and not allow any fuel back to the air filter base.
A tank vent that is stuck closed will not allow air to the tank... However, a tank vent that is stuck open can and will cause fuel to be spit back to the air filter base.
So, is the fuel coming from the carburetor venturi (A in the picture) OR the tank vent line fitting in the air filter base (B in the picture)?
Is fuel is coming from A? If so then it would only be a carburetor issue.
Is fuel is coming from B? If so then a new carburetor would do no good as it is a tank valve that is stuck open (C in the picture).