Small Engines (Lawn Mowers, etc.): Yard Machine By MTD Briggs & Stratton Motor, carburetor adjustment, briggs and stratton

Question
QUESTION: My lawn mower will turn over but it will not stay started.   My friend cleaned the carburetor and changed the spark plug, and put some new gas in it because he thought that the gas was bad.  The day that he done all of this it ran.  Now it will turn over but will not stay started. He also has to prime it for it to turn over each time he tries to start it. Any suggestions."

ANSWER: Hello Amanda:

It Could be as Simple as a Carburetor Adjustment. Send me the Model Numbers Off the Engine, Please. With these I can Locate the Proper Manual and Better Assist you. Thanks.

Respectfully

John

---------- FOLLOW-UP ----------

QUESTION: Ok the Model # is 12A-378N302 and serial # is 1B117K90734 in case you need it.    

Thanks,

Amanda

Answer
Hello Again Amanda:

These Numbers are for the Mower. The Mower Breakdown Does Not List the Engine Model Numbers for your Mower. Look on the Blower Housing (metal engine cover) Above the Spark Plug. There Should be 3 Sets of Numbers Stamped Into the Housing. They are Similar to these; Model #12H707, Type #0141-01, Code #9034571. Send me the Engine Numbers, Please. Thanks.

Respectfully

John

Hi Amanda:

I Located the Engine Model Numbers in the File. Sorry. They had them Hid from me. lol. You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.outdoordistributors.com/ and Select the B. Then Select Briggs and Stratton. Then Select Don't have Part Numbers. Then Select the File # 12. Then Select the Folder # 12H800. On Page 3 of 18 Breakdown/IPL #'s 94 is the Idle Air Mixture Screw. If it is Not Set Properly, you will have the Problem you Described. The Following is the Instructions on Setting the Screw. Even though the Instruction are for 2 Air Mixture Screws; Set Just the One the Same as the Instruction Suggest. Ignore the Parts that Do Not Pertain to your Carburetor. **All the Carburetor Adjustments are the Same for Lawn Mower and Trimmers. There are Several Location for the Air Mixture Screws. The Idle Air Mixture Screws are Usually Located at the Top of the Carburetor Bowl and the Top of the Carburetor Body. If the Main Air and Idle Air Mixture Screws are Side by Side on the Side of the Carburetor, then the Idle Air is the Farthest from the Engine. The Main Jet Air Mixture Screw is Located in the Bottom of the Carburetor Bowl or Beside the Idle Air Screw on the Side of the Carburetor Body. Some of the Older Model Carburetors have the Main Jet Mixture Screw Straight in from the Top of the Carburetor Body (this is Rare anymore). If you have Cleaned the Carburetor (Disassembled and Soaked Overnight in Carburetor Cleaner (I Use Gunk). Then Blow Out the Passages with Compressed Air and Install a New Kit if Required. Now Setting the Air Mixture Screws:  ****Turn the Idle Air and Main Air Mixture Screws In Until SNUG **Don Not Jam** Then Reverse Both Screws 1 1/2 Turns. Holding the Throttle Full Open, Start the Engine. Turn the Main Air Mixture Screw Clockwise Until Proper Revs are Obtained. 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 Mixture Screw so there is No Hesitation when Throttling from Idle to Full Throttle. Reset the Engine Idle if Required.**  Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks.

Good Luck

Respectfully

John

Hello Amanda:

Hope All is Good. Just Checking. I thought you Might have Thought I Sent you the Same Answer Twice.

Respectfully

John