Small Engines (Lawn Mowers, etc.): No spark on an Ariens tractor, ariens lawn tractor, keyswitch

Question
QUESTION: Hi,

I have an Ariens lawn tractor (model 935030) with B&S 12 hp engine. When I tried to start it a few days ago, the engine cranked but wouldn't turn over. I replaced the spark plug with a new one, checked for spark but there is nothing. I tried removing the stop wire but still no spark. All the wires seem ok. Maybe I should mention that instead of a normal keyswitch, I usually start the engine with a momentary push-button and stop it with another button. (the original keyswitch was completely worn out, so I replaced it with this system which worked fine for months) Now I notice that when I push my "stop" button, the 15 A fuse blows. I removed the stop button but the tractor still won't start. Any help would be greatly appreciated!

thanks in advance

Martin

ANSWER: Hello Martin:

Remove the Spark Plug. Wrap a Wire Around the Threads and Attach the Other End of the Wire to the Engine Block Turn the Engine and See if the Plug Fires. If No, then Disconnect the Shut Off Wire  at the Control Bracket First, Check for Fire at the Plug. If Still No Fire at the Plug; Then Disconnect the Shut Off Wire at the Coil (usually requires removal of the blower housing) and Check for Fire at the Plug. If No Fire at the Plug , then the Coil/Ign Module is Bad. The Coil/Ign Module to Flywheel Gap is .020in. On Some Model JD Engines, there is a Igniter that Goes Bad and Not the Coil. The Igniter is the Same as an Ignition Module. If the Plug Fires at Anytime During these 2 Checks, then a Safety Switch or Wire May be the Problem. Yes the Engine will Turn Even with a Bad Safety Switch. The Blade Safety is Usually the Cause of this. The Starter Turns and The Engine Doesn't Fire is an Indication of a Bad Coil/Ign Module or a Faulty Blade Safety Switch. The Clutch Safety Prevents the Starter from Engaging so the Mower Does Not Move when the Starter Turns the Engine. The Seat Safety is Designed to Stop the Engine if the Blades are Engaged or the Clutch Safety is Not Engaged when you Leave the Seat. Where is the Stop Button Connected to on Each Lead? One Side should be for the Coil Grounding Wire and the Other to Ground on the Battery or the Frame/Engine. You can View a Breakdown of the Mower at this Site Addy; http://www.jackssmallengines.net/parts.asp and Select Shop Online Parts Look Up. The Select the Model Tab. Then Select the OEM (Ariens) and Enter the Model Numbers. Then Double Click on the Model in the Results Area. You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.smallenginepartswarehouse.com/parts.asp and Select the Shop Online Parts Look Up. Then Select the Model Tab. Then Select the OEM and Enter the Model and Type Numbers. Then Double Click on the Model in the Results Area. Now you can Select the Section of the Engine you Wish to View. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. 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 9pm EST (US). My New Day Starts then. Thanks.

Respectfully

John

---------- FOLLOW-UP ----------

QUESTION: Hi John, thanks for your answer.
I checked for spark with the stop wire disconnected and there was no spark. Does that mean that the problem is not with any of the safety switches, or should I bypass them to make sure? Also, is there any way I can test the module/coil with a multimeter? Thanks again

martin

Answer
Hi Again Martin:

If the Magnet on the Flywheel is in Place and you Disconnected the Shut Off Wire from the Coil/Magneto/Ign Module and the Engine Still Does Not Fire the Plug, then the Coil/Magneto/Ign Module is Bad and Requires Replacing. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. Thanks.

Good Luck

Respectfully

John