If look on your wiring diagram, you will find a relay (probably I.D.'d as #1) that is labeled "stop relay". As part of your troubleshooting, you should check that this relay is operating properly. After that, the ignition coil could be bad. Good luck - RAY
P.S. - I'm not sure
if this relay grounds or ungrounds the wire from the ignition coil to kill the spark.
Need additional input from someone more knowledgeable on this.