Small Engines (Lawn Mowers, etc.): tilloston, carburetor jets, jonsereds

Question
have a jonsereds 670 and here is my problem. first let me tell you although not a paid meckanic i have ben doing this along time and i am bafiled. my carb is all clean new parts etc .saw runs i while 20-30 seconds fine respondes to the fuel mixtures fine .then for no reacon becomes super rich.  take the crb off and it is flooded inside. have done this so far. put another new needle in and diaframe kit no change  cleaned fuel lines cleaned and checked the return line checked the fuel pump end and changed it again  nothing . saw most be started wide open  ith no choke so i no it too rich any idea's?

Answer
Hello Gaston:

1- Have you Checked the Exhaust Port and Muffler? Remove the Muffler and Inspect the Exhaust Port for Carbon Blocking the Exhaust Port. Check the Muffler and Spark Arrestor Screen (in the muffler) for Blockage Also. If the Exhaust Port or Muffler are Restricted, then the Engine Can  Not Exhaust and the Carburetor will Flood the Engine. 2- If the Carburetor Pulse Pump Needle is Set too High, then the Carburetor will Flood from the Pump Allowing too Much Gas to Enter the Carburetor Jets. 3- Check for Fire and Make Sure it is Firing Properly and Not Intermittently. I have had Some Ign Modules/Coils that Fire the First 30sec to 1 Minute and then Stop Firing the Plug and this Causes the Engine Flooding. I Suspect the Needle is Set to High and Not Stopping the Gas Flow Properly. The Needle is Set so it Just Touches the Diaphragm. The Jonsered Brand is Now a Husqvarna Outdoor Products Unit. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John