They now have B&S start on the first pull. Push the primer ONLY 3 rimes, and they start on the first pull. Old priming systems where just a bypass system. Once the carb cavity was full all the pumping you did retuned fuel to the tank. New primers put fuel in the carb, just as if you would squirt some in. That's why the usually start on the first or second pull. Some even without choke.