I have a Murray rear-engine riding lawn mower with a Briggs & Stratton 875 Series (190 cc) electric start engine. When cold, the mower starts up first try and runs well. After a few minutes, it begins to sputter and dies shortly afterwards. It begins smoking pretty bad as it is sputtering/dying. It does start back up after a few tries, but it immediately begins smoking and sputtering and then dies. I have tried running it without the air filter with no change.
Several things could be the cause with your limited explanation of the symptoms. To further refine things, you should do the following:
-check the spark plug and describe what it looks like
-check the oil and describe it's looks and level
-do you smell gas after the shutdown
-how long until it starts again, and what is the engine temp when it starts?