i could understand pressure from the sun heating the tank if the breather is closed, but this would only flood the motor when you first try to start it. after running it should be all good until it creates enough vacuum to not supply fuel (assuming you've forgotten to undo the breather screw)

i think you're doing the right thing though by asking a technician neil, don't forget to ask him where the idle air screw should be and ask what range you can move it without causing harm.