Well, here's an update. I came to the conclusion that the prob is the new top cover, Briggs part number 495035. I filled the bowl with gas and unplugged the fuel line and started the engine with the original cover and it ran fine till it ran out of fuel. The new top cover is somehow different. The part number in my owners manual on the breakdown of the carb parts is 499281 which I can't find. Some of the websites show that the new part number is 693483 but it looks different in the pics. Anybody know where I can find an original 499281??