Small Engines (Lawn Mowers, etc.): tiller, gilson tiller, briggs and stratton

Question
I have a Gilson tiller Model51148 with a Briggs and Stratton model 130292 type 0803 01 80080506. I was able to get it going after it sat for a couple of years. Used it for about two hrs when it backfired and quit. Didn't have any spark so I put new points and condencorin. Started and ran for a few seconds and quit. No spark so took it apart and found the key sheared in half that holds the flywheel on the shaft. Replaced key and the same thing happened. Can you help me out.
Thanks Mark

Answer
After setting for a few years it could be anything.  Are the points set correctly with a feeler gage?  Is the plunger is good condition.  Is the air gap set correctly on the coil? Did you replace the spark plug?  Is there resistance in the coil if measured with a continuity meter? Have you checked timing inside the engine?

If the answer is yes to all above then I would start with the carb.  Disassemble and clean.  Install new kit and reassemble with new gaskets.  Clean tank and pick up tubes inside the tank.  Clean the fuel cap.  Adjust the throttle and choke and be sure the kill wire is attached to the panel on the carb.  Give this a try and let me know if it isn't it.