Small Engines (Lawn Mowers, etc.): CV12.5s - 12.5 Kohler command, adjustment screws, carburetor body

Question
Good Evening John –

My situation is with a STX 38 (CV12.5s - 12.5 Kohler command).  It has been a great little work horse but suddenly as I am mowing it loses power and kills.  I choke the engine and it restart. Run at fine for 5/10 minutes then starts to sputter.   It also seems to lose poser on the small (very small) hills in my yard.  

Respectfully,
John

PS:
I have changed the following – the standard maintenance items.
Oil
Spark plug
Oil filter
Gas filter


Answer
Hello John:

When was the Carburetor Last Cleaned? For the Carburetor: The Carburetor, the Carburetor Shut Off Solenoid and the Stator can All Cause the Problem you Described. However, this being a JD; Check the Pickup Tube in the Tank. The Screen May be Stopping Up with Rust Flakes and Other Debris. You can View a Breakdown/IPL of the Mower at this Site Addy, http://jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.H... and Enter the Model Numbers and Click Find. Then Select the Sectional File. Then Select the Section of the Mower you Wish to View Online. For the Carburetor:  Remove, Disassemble and Soak the Carburetor Overnight in Carburetor Cleaner (I Use Gunk). I have Found that Most People can Use a Breakdown/IPL and Disassemble the Carburetor Enough for Proper Cleaning. You Only have to Remove the Bowl, Float Pin, Float and Needle Valve and Any Adjustment Screws that Go Into the Carburetor Body. The Welch Plugs Do Not have to be Removed. Then Soak the Carburetor Body and Parts in a 1 Gallon Can of Gunk Carburetor Cleaner Overnight. The Can has a Parts Tray Inside it for the Small Parts. Once the Carburetor and Parts are in the Cleaner, you can Replace the Lid for Safety and to Prevent Accidental Spillage. Then Blow Out the Passages with Compressed Air. Install New Parts if Required. If the Stator is Not Charging Properly, then the Carburetor Solenoid will Slowly Start to Restrict the Gas Flow to the Carburetor Jet and the Engine Acts as you Described. With the Engine Running at Full Throttle, Check the Battery Voltage. It Should Read 13.2 VDC or Higher. If the Carburetor Solenoid is Heating Up it will Restrict the Gas Flow as you Described. Remove the Carburetor Solenoid and Go to the Hardware Store. Purchase a Bolt of the Same Diameter and Threads. It Needs to be 3/4" Long. Put this Bolt in Place of the Solenoid. If this Corrects the Engine Problem, then Replace the Solenoid. ***NOTE: THIS IS FOR CHECKING THE SOLENOID ONLY I NEVER SUGGEST YOU OPERATE THE ENGINE WITH THE SOLENOID OUT OF THE CARBURETOR EXCEPT FOR TESTING PURPOSES*** Sometimes the Plunger is Moving, Just Not Far Enough to Allow the Gas to Enter the Jets. 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 your Question at or Just After 9pm EST (US). My New Day Starts then. Thanks.

Respectfully

John