Small Engines (Lawn Mowers, etc.): Yardman leafblower, air mixture, question pool

Question
Have 3 yr. old. Yardman blower model YM320BV. Changed plug, cleaned air cleaner and spark arrestor. Starts good. Follow instructions, prime 10 times, pull in position one 2-3 times, switch to position 2, starts in 1-2 pulls. Have let warm up for as long as 20-30 minutes, but when I switch to position 3, it dies, like it is being choked. Back to 2, and it runs fine. Any ideas?     Thank you

Answer
Hello Bill:

>>Sorry for the Delay. This Question was Located in the Question Pool and I can Only Answer Questions from the Question Pool when I am Not Answering My Questions here or at the Other Site I Answer Questions at.
>>From your Description it Sounds like the Carburetor Mixture Screws Require Adjusting, or the Exhaust Port or Muffler is Slightly Restricted and Require Cleaning/Replacing.
>>The Following is a Basic Instruction File for Doing a Diagnostic on the Engine for this Problem. Any Input is Appreciated.
>>**Remove the Muffler and Make Sure the Exhaust Port is Clear.
>>If it is, then Try to Start the engine with the Muffler Off.
>>If it Starts and Runs Properly, then Clean the Spark Arrestor Screen in the Muffler or Replace the Muffler if Required. Some Mufflers will Split apart for Cleaning of the Screen and Some are Screwed/Bolted to the Outside and on Others the Muffler has to be Replaced.
>>The Following is the Instruction File for Setting the Air Mixture Screws. Any Input is Appreciated. The Procedure is the Same for 1 or 2 Mixture Screws, Just Use the Instruction File and Skip Over the Section with the Missing Mixture Screw ( Usually the H Mixture Screw).
>>Now Setting the Air Mixture Screws:  
>>****Turn the Idle Air (L) and Main Air (H) Mixture Screws In Until SNUG **Do Not Jam** Then Reverse Both Screws 1 1/2 Turns. Set the Throttle Full Open, Start the Engine.
>>Turn the Main Air (H) Mixture Screw Clockwise Until Proper Revs are Obtained. **Carefully Use your Finger and Move the Governor Arm to Rev the Engine (on Chainsaws and Trimmers Use the Trigger to Rev the Engine) Until you Reach Max RPMs (on Chainsaws and Trimmers, the RPMs are Not Set to MAX. Set to Max and then Reverse the Setting Screw 1/4 or 1/2 Turn. If the H Mixture Screw is Set too High; the Engine will be Starved for the Oil in the Gas and Damage the Piston and Jug/Cylinder) and the Engine is Running Proper at Full Throttle Up a Grade and for Chainsaws and Trimmers they Do Not Bog Down Under a Load. Occasionally you May have to Turn this Counter Clockwise to Achieve the Proper Revs.**
>>Now Allow the Engine to Idle. Set the Engine Idle Screw (Not Idle Air) so the Engine will Stay Running if Required.
>>Now Set the Idle Air (L) Mixture Screw so there is No Hesitation when Rapidly Throttling from Idle to Full Throttle. Reset the Engine Idle if Required.****
>>If you Hit a Snag or this Does Not Correct the Problem,  I Hope to be Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Be Safe and Happy. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 3 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. All Follow up Questions are Accepted at Any Time. Comments and Ratings are Greatly Appreciated. Thanks.

Respectfully

John