Brand new Briggs and Stratton cr950 won’t start. Mechanic's Assistant: When did you last change the oil? Its brand new out of the box. The oil is new. Mechanic's Assistant: How long has this been going on with your Briggs & Stratton? What have you tried so far? It has never started. Briggs and Stratton 4 Causes Why Briggs and Stratton Engine Starts but Won’t Stay Running! After a few failed attempts at running your Briggs and Stratton mower, please take a break! You have to inspect the relative parts which can prevent the start of the engine. After finding the cause of the lawn mower parts, you’ll easily fix this problem. own a troy-bilt mower, model TB360 ex with a Briggs & Stratton 190cc, 875 series motor. Son attempted to put a quart of oil in the motor which caused it to not run. Motor fuy drained and cleaned but t … 0UaYA.