Small Engines (Lawn Mowers, etc.): wont start, briggs and stratton, air gap

Question
Hi John i have a Murray ride on with a 10hp briggs and stratton 28A707 0113 01 961015ZB the mower has been running perfectly untill last sunday  when it just refused to start.i have run all the usual checks spark fuel ect there was no spark  took the kill wire off and still no spark so replaced the coil with a new one also replaced the plug with a new one  i have bridged all the kill switches (3 of ) i set the air gap at 10thou still no go ..took the kill wire off and there is a spark albeit a weak one there is plenty of fuel getting to it  and its fresh fuel even tried spraying quick start in the carby  ..nothing..i have run out of ideas so anything you can suggest will be much appreciated..about ready to send it to the shop  but hate things getting the better of me
Ken

Answer
Hello Ken:

Run a Ground Wire from the Engine Block to the Frame. Oil and Dirt gets Under the Engine Mounting Pads and Cause a Weak Engine Ground and this Causes a Weak Spark from the Plug if the Coil is Good. What is the  Engines Compression? The Following is a Basic Instruction File I Made for Checking the Coil/Ign Coil/Magnetron on Small Engines. Any Input is Appreciated. **To Check the Ign Coil; Remove the Spark Plug/s. Wrap a Wire Around the Threads of the Plug and Attach the Other End of the Wire to the Engine Block. Remove the Blower Housing (metal engine cover). The Wire that is Connected to the Coil/Ign Module from the Shut Off Switch needs to be Removed (unplugged) from the Coil/Ign Module. Now Check for Spark at the Plug. If Spark, then the Shut Off Switch or the Wire is Bad. If Still No Spark, then the Coil/Ign Module is Bad. If there are Safety Switches on this Unit and the Coil is Good; you Need to Check the Safety Switches for Being Bad Also. The Ign Coil is Gapped to .020in from the Flywheel.** The Following is an Instruction File for the Safety Switch System. Any Input is Appreciated. The Color Code of the Wires May be Different than those I Use as a Reference in the Instruction File. **PLEASE REMEMBER THAT THE INSTRUCTIONS FOR CHECKING THE SAFETY SWITCHES IS JUST THAT!!! FOR CHECKING ONLY. I NEVER Suggest a Mower be Operated with a Safety Device or Switch Disconnected or Bypassed. Now. On Some Model Mowers you can Simply Unplug the Safety Switch from the Harness. On Other Models you have to Place a Jumper Wire Between the Harness Terminals (on the 4 Post Switch (Clutch/Brake) Jumper from Same Color Wire white to White First and then Check for Fire, Now Include the Black to Black Wires if No Fire. Check the Clutch/Brake and the Blade/PTO Safety Switches First. Check the Seat Safety Last. Usually the Seat Safety is Not in the System for Starting the Engine. Just to Ensure Someone is in the Seat when Engaging the Transaxle and/or Blades. Use a Paper Clip or a Short Wire to Make a Jumper.** Please, Do Not Hesitate, 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. May the All Mighty Bless You and Yours. 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. Comments and Ratings are Greatly Appreciated. Thanks.

Respectfully

John