I have a toro z master 253. It want start on its own. Ive teated all the safety switches the alternator and the rectifier. They test fine. If i try to start it it wont fire and run, but if i hook the charger to it it will fire and run. It has a new battery, starter and solenoid. If i ground the plug wire to the engine i dont get a spark, but if i hook the charger to it i get a weak spark but enough for it to fire and run. would that mean my coils are bad. Any info would be appreciated. Thanks, Jeff.