My mower is a Craftsman 18hp with a Briggs Stratton 31C700 Engine with a Nikki Carburetor. I could be mowing and my mower will cut out. If I wait a while, about 30 mins, it will start again and repeat lthe problem. One thing I did was to disconnect the gas line and blow in to the carburetor and it seems like it clogged, like the float might be stuck closed. If I take it apart, it is very clean, no clogs. I actuate the float up and down sereral time and it doesn't stick, so that doesn't seem to be t he problem. It's like something shuts the gas down and won't let it in the carburetor.