Small Engines (Lawn Mowers, etc.): B & S 18.5 with carb issues?, engine rev, float valve

Question
Hello John -- I have a Sears 18.5 B&S 31P777 0296 with about 100 hrs.  Fuel suddenly started to free flow the carb - and elsewhere  -- creating some interesting starts -- lots of black smoke.  Pulled the carb (Walbro) to check on the float valve, which I believed to be the problem.  Cleaned the carb (but did not rebuild).  The carb appeared to be quite clean.  Reinstalled and started.  The engine rev'ed very high, even though the throttle was set on low.  I killed the engine for fear of blowing it, as it seemed the governor was not functioning at all.  Only by manually moving the governor control lever fwd can you get the revs to normal.  Of course, unless I set up a 'counter spring' on the lever, this is an impractical way of controlling the revs.  I read someplace that the breather assembly (tube, reed) might not be functioning.  Possible?  If so, how does one determine if it is working?  What does it do? How is it repaired?  Couple of points:  spark plug is black.  Fuel pump is new.  Thanks!

Answer
Hello Gordon:

Did you Disconnect the Governor Arm From the Governor Shaft when you Removed the Carburetor? If yes, then the Governor Need to be Reset. To Reset the Governor; Loosen the Governor Arm Bolt and Turn the Governor Shaft Clockwise Until it Stops. Using the Governor Arm Hold the Carburetor to Full Throttle. Now with the Shaft Full Clockwise and the Governor Arm and Carburetor Held at Full Throttle, Tighten the Governor Arm Bolt. If No, then the Internal Governor May have Broken. If the Governor has Been Reset and the Engine Still Runs Full Throttle, then Move the Governor Arm by Hand. Do you Feel A Push Against your Hand When you Slow the Engine? If the Internal Governor is Working you Will Feel a Push on the Governor Arm when you Throttle Down the Engine. You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.smallenginepartswarehouse.com/parts.asp and Select the Shop Online Parts Look Up. Then Select the Model Tab. Then Select the OEM and Enter the Model Numbers 31P777-0296. Then Double Click on the Model in the Results Area. Now you can Select the Section of the Engine you Wish to View. Are you Sure the Throttle Linkage is Connected Correctly? Is the Governor Spring on the Throttle Bracket Attached to the Governor Arm? The Throttle Cable Attaches to the Throttle Control Bracket. The Cable Moves a Slide that Moves a Piviot. **On Some Models the Slide Simply Pulls the Spring that is Attached to the Governor Arm.** The Piviot 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 Piviot and the Piviot Pulls the Spring. The Spring Pulls the Governor Arm and the Governor Arm Moves the Throttle Shaft. Hope this Helps. I am Here if You Require More Assistance. 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 you Question at or Just After 9pm EST (US). My New Day Starts then. Thanks.

Respectfully

John