Clean out the carburetor main jet passage with some spray carb cleaner (and compressed air if available).
This problem occurs sometimes after a "fuel out".
When the fuel is gone from the tank, the engine runs its last few seconds on just the fuel in the float bowl.
Under these conditions, water and sediment that might have been loitering on the bottom of the bowl can get roiled up and be drawn into the main jet and block the flow of fuel.
It has been said that after refilling the tank with fuel, the inrushing flow of fuel into the empty bowl is what stirs up the dregs of junk from the bottom of the bowl.
It would be fair to say a little of both take place if any junk is present in the bowl.
The "switch" you are referring to is the anti-after fire, fuel solenoid.
The main jet is what the solenoid seals off with the little plunger on the end of the solenoid when the key is turned off.