Small Engines (Lawn Mowers, etc.): STIHL O11AV wont start, fuel line filter, blue spark

Question
I have a STIHL 011AV chainsaw about 20 years old with only about 20 hours use total.Put fresh correctly mixed gas in it started right up than quit after about 2 minutes.won't start even when putting fuel into plug hole.Put in new plug correct gap,new fuel line,filter, has good compression strong blue spark, rebuilt carb still won't fire up even by adding fuel into plug hole.Any help on this would be appreciated.

Answer
 Hello Bill:

 Have you Removed the Muffler and Checked the Exhaust Port for Blockage from Carbon. Check the Muffler and Spark Arrestor Also. Other than the Muffler and Exhaust the Only thing you haven't Covered is the Flywheel Key. If the Key is Damaged it will Throw Off the Plug Timing to the Piston. Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks. Be Safe.

 Good Luck

 Respectfully

 John