Small Engines (Lawn Mowers, etc.): Motor starts then stops, float bowl, model type

Question
I've got a 5 year old mower with a Briggs motor.  After only a few minutes tonight, it stopped unexpectedly.  It would start after several pulls, run for less than a minute and die out.  I took off the air filter holder and the top corner cover.  I sprayed all the grime off with carb cleaner and had someone start it.  I don't know the parts, if you can't tell by now, but there is a flange attached by a spring.  I noticed that it started up, ran for a few seconds, then the flange moved and the motor stopped.  Almost seems like a sensor told it to stop sending gas to the motor.  There isn't an issue with the gas line.  I found out because I started to loosen the float bowl and gas started to come out of the float bowl.  I quickly tightened it back up.

I assume I should drain the gas before I do anything else.

Answer
Hi Wayne
 Without knowing the model # Type # and code # from the engine, I will have to be very general. It sounds like you may have a blockage in a jet or port inside the carb interrupting the flow of fuel to the engine. The carb would need to be removed and every jet and port cleaned and opened up. Hope this helps.