Part not found???? Air Cleaner or something else.

Run for five seconds and shut down could mean it is burning the prime fuel and then not getting enough fuel from the carb to keep running. Most likely will require carb teardown and clean and repair with carb repair kit. The rubber bowl gasket tends to swell when exposed to gas, and also the rubber valve seat can swell and shut off fuel flow into the carb bowl.

Don't forget the 'small rubber hose.'

It has to go somewhere. It can't be left dangling, open to the atmosphere or your engine's life will be a short one.