Hi Jeff,
I am having the same problem basically with my 20.5 Briggs & Stratton Craftsman Riding Lawn mower, it will turn through with the starter, so the starter is engaging and turning the engine through, however it will not crank ( Ignition Issue ) I checked and it is getting fuel but no fire. I am an aircraft electrician by trade, however I dont have a wiring diagram for the tractor, so I followed out the circuits
physically and jotted them down on paper, could not find anything here on the internet in regards to the wiring ( at least where someone did not want a few bucks for one ) at any rate, I do understand that the mower has safety switches for the seat position, which must have someone setting in it to start ( Seat Compressed to "OPEN Switch Contacts", also the Clutch / Brake pedal must be depressed to "Open Switch Contacts" and of course the PTO as it is referred to by some on the net here, I am calling it the Blade Drive Engagement Switch, it must be disengaged to start the engine. Now all that being said,, these are all safety switches that either prevent the starter motor relay from energizing or Kill the ( Coil Pack Assembly ) "Magneto" in this case, the coil pack "Magneto" has your spark plug wire coming from it and also has a Single Electrical Terminal that contains the KILL WIRE, if this wire has a Ground on it at anytime the Coil Pack or Magneto is not going to provide any fire or Spark, check this with an Ohmmeter, now if you remove the KILL WIRE from the terminal of the Coil Pack "Magneto" then you have defeated the Safety Switches and Stop circuit, try cranking the mower, if it cranks this should give you a confirmation that the Coil is ok and there is yet an issue with the Safety Switches, it is a good isolation as to whether the Safety Switches or killing your ignition source. Of course if it does not start at this point with the KILL WIRE removed from the coil pack then you will need to replace the Coil Pack "MAGNETO" ... so it is one or the other and could even be issues with both, however when the coil pack has the KILL WIRE removed at first stages of trouble shooting this will confirm the condition of the coil pack itself, and you get the picture there after...
I am going to talk with the Sears service Dept and see if I can yet obtain a Wiring Diagram, if not I will create my own from a reverse engineering standpoint, it wont be the first time I have had to do such a task....
I hope that helps you out to some degree Jeff...
Cheers and Good Luck...
Tommy
Tommy, April 2007
