Small Engines (Lawn Mowers, etc.): run-away idle on a 10 HP Tecumseh, throttle shaft, tecumseh engine

Question
I have a 20+ year old Craftsman 36" lawn tractor with a 10 HP Tecumseh(engine part #143.366062). The carburetor has been worked on many times over the years (cleaned  & rebuilt,etc.) but only the last year has it been uncooperative. After the engine starts, I can’t get it to idle down using the throttle cable. I can get it to idle by forcing the throttle closed but if I snap the throttle, the engine races & it won’t return to idle speed. I checked the throttle spring & it seems weak or loose but not broken. The lower bent end of the spring seems to have come loose or unwound, but from where? Also there seems to be a lot of side play in the throttle shaft. Could it be so worn that it’s letting air in past the shaft & making the idle uncontrollable? Do I need a new carb or am I “barking up the wrong tree”?  Thanks in advance for your assistance.  Woody

Answer
Hello Woody:

Check the Throttle Control Linkage First. the General Description and the PDF Site Addy that Follows will Help in this Check. **The Throttle Cable Attaches to the Throttle Control Bracket. The Cable Moves a Slide that Moves a Pivot. The Pivot has the Spring  Attached to it and to the Governor Arm. The Solid Link Connects to the Governor Arm and goes to the Throttle Shaft on the Carburetor.  When the Throttle Cable is Moved it Moves the Pivot and the Pivot Pulls the Spring. The Spring Pulls the Governor Arm and the Governor Arm Moves the Throttle Shaft. Usually the Spring is in the Lower Hole in the Governor Arm and the Solid Link is in the Top Hole of the Governor Arm.** You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.outdoordistributors.com/ and Select the T. Then Select Tecumseh. Then Select Don't have Part Numbers. Then Enter the Model Numbers. Then Select your Model and Download the File for Online Viewing. Since this is a Tecumseh Engine, I have a PDF Site Addy that May Assist you Also. http://www.tecumsehpower.com/CustomerService/BSI.pdf Depending on the Side Play in the Throttle Shaft, it can be the Cause of your Problem. As you Mentioned, if the Throttle Shaft is Allowing Air through Around the Shaft, then you will have an Idling Problem. Some of the Newer Carburetors have a Plastic Bushing that can be Replaced when this Occurs. 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. 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