p/v
Pull the Bowl off,turn the Plate on end that the Power valve is Down.Put some type of Thin Liquid(Carb Cleaner,Brake Kleen)in the Threaded hole that the Valve Screws into,if it runs Threw,the Diapham is Bad!
Or you can use a Vac.Pump.They actually make a P/Valve tester.But,you can usually see if they are Blow!
Hope this HELPS?
Later
G 8)