Small Engines (Lawn Mowers, etc.): Wiring, spark plug wire, jumper wire

Question
I have a PowerPro 18 Horse Power 42" Lawn Tractor Briggs %26 Stratton engine. It would not start, when I turned the key over it did nothing. i have replaced the ignition, and also the part that the battery and starter are connected to. If we cross jump it it will start, but it will not start just by turning on the key. The lights come on and everything seems to be fine except even with the new parts on it, it will still not start. The serial number is 0919944002003  Lt4218 Lt4218B is the model
I would like to thank you in advance for your answer and your help in this matter.

Answer
Hello Anita:

>>Always Remove the Spark Plug Wire/s from the Spark Plug/s before Working on Any Small Engine unless the Plug/s must be Connected to the Coil/s for Diagnostic Reasons.
>>From your Description it Sounds like the Blade or Clutch/Brake Safety Switch has a Bad Connection or is Bad and Requires Replacing.
>>The Safety System on the Unit is Showing that one of these is Engaged and will Not Allow the Ign Switch to Operate. This is How the Safety System is Designed to Function.
>>Check the Safety Switches.
>>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 (Example: 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.  Then Check the Oil Guard Switch (if Applicable). 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.**  
>>Use a Multi-meter and Check the Continuity of the Switch. The Meter should Show when the Contacts are Closed and Open. The Meter will Swing All the Way Over when the Switch Contacts are Closed and Swing Back to the Rest Point when the Switch Contacts are Open.
>>You are Very Welcome for Any Assistance I can Provide.
>>If you Hit a Snag or this Does Not Correct the Problem,  I Hope to be Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Be Safe and Happy. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 5 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