No spark at plug

[stonum]

My riding lawn mower is an older Craftsman, model 917.271131. Motor is a Kohler model CV16S. It's always run good till recently. The starter turns the motor, but there is no spark at the plug. (I held the plug against the block and turned the starter to look for a spark). I've looked and looked for any loose electrical connections. Tried new plug and new coil with no luck. Any ideas on what to try next? Thanks

 

[ILENGINE]

The spec number along with the engine model number would be helpful so we can look up the correct engine. Also if this has the single wire coil unplug it and crank the engine. No spark then bad coil or plug. the reason I ask is some of the CV16 has smart spark ignition on them.

 

[StarTech]

OM says it came with spec 43527

 

[ILENGINE]

OM says it came with spec 43527

If that is the correct spec then that is a DSAM engine so may need the 12 707 01-S DSAI conversion.

 

[stonum]

I'll look for the spec today. Does that safety kill switch under the seat ever go bad? I'm going to take a look at that safety switch today. And ILENGINE, can you tell me more about the 12 707 01-S DSAI conversion? Where is that kit available at?

 

[Bertrrr]

Safety switches will not let your starter engage so not a safety switch issue , clean the magnets good on the flywheel and the coil where it relates to the flywheel magnets. There is a ground wire at the coil you can pull off and see if it sparks then , if it does it's not the coil

 

[StarTech]

The particular seat safety does goes bad as they run 12V through it the activate a relay which in turn disables the ignition coil circuit. So basically normal operation will require someone to be on the seat in order for the ignition coil to fire the plug.

Now with this said either seat switch or the operator present relay can be bad. To check the seat switch at home you turn the ignition switch and sit on the seat while listening for the fuel solenoid on the carburetor to click. If it clicks then the seat switch is good and probably the relay is bad. And I have seen these relay fill with so much rust that can't operate which mimic a failed seat switch. Also there a second operator present relay which normally provides engine braking via the stator upon either when operator is off the seat or you are shutting the engine by turning off the ignition switch. Also the seat switch is bypassed once the engine is running with the brake/clutch pedal up/released and the deck is engaged which creates an unsafe operating condition. A third operator present relay completes the battery charging circuit.

Your wiring schematic

 

[StarTech]

Safety switches will not let your starter engage so not a safety switch issue , clean the magnets good on the flywheel and the coil where it relates to the flywheel magnets. There is a ground wire at the coil you can pull off and see if it sparks then , if it does it's not the coil

Bert, You should look at the schematics and understand it before taking a wild guess at the system operation.

Also rust doesn't affect magnetism; though, it affects electrical conductivity and clearances.

 

[ILENGINE]

Safety switches will not let your starter engage so not a safety switch issue , clean the magnets good on the flywheel and the coil where it relates to the flywheel magnets. There is a ground wire at the coil you can pull off and see if it sparks then , if it does it's not the coil

Little more complicated than that. On his engine he either has the DSAM which supplies 12 volts to the coils, as well as impulse controls and has 2 terminals. The DSAI conversion also supplies 12 volts to the coils and has 3 terminals. You can't just unplug them and make it work like the single wire to ground to kill the system.

 

[ILENGINE]

I'll look for the spec today. Does that safety kill switch under the seat ever go bad? I'm going to take a look at that safety switch today. And ILENGINE, can you tell me more about the 12 707 01-S DSAI conversion? Where is that kit available at?

Here is one possible place to get the DSAI system if you need that setup

Amazon.com