No spark at plug

[StarTech]

And this gives a better idea of how the DSAI coils are wired.

 

[stonum]

To add to my fun, my alternator in my car went out this morning. So now, I'm trying to deal with 2 things at once. Plus, it's raining and cold and dark here. Anyway, here's some pics of my mower. It needs a washing, but it's just too nice a mower to give up on. I put on new belts and tires and battery, and fuel filter, ect... just 2 years ago. It's run so well up till now.

 

[Bertrrr]

Good to have the schematics to reference Thanks for your input

 

[ILENGINE]

To add to my fun, my alternator in my car went out this morning. So now, I'm trying to deal with 2 things at once. Plus, it's raining and cold and dark here. Anyway, here's some pics of my mower. It needs a washing, but it's just too nice a mower to give up on. I put on new belts and tires and battery, and fuel filter, ect... just 2 years ago. It's run so well up till now.View attachment 68471View attachment 68472

That is the Digital Spark Advance Module or DSAM for short. It controls spark timing and advancement. When it fails can cause a no spark issue. When doing the DSAI conversion that box can be removed and tossed in the trash because the conversion doesn't use it.

 

[stonum]

I threw a new alternator in the car Friday, so now I can start looking closer at my mower, using the info you all have provided. Or I can go to Home Depot and buy a Murray MT 100 42 in. 13.5 HP for $1700, which isn't in my budget at all. Everything on my Craftsman works so good, I just got to get that plug sparking. Trying to cut my big lawn with my walk-behind is a major pain.

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[billbud]

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

I would check the air gap

 

[VegetiveSteam]

CV16 engines with no spark issues are mostly unheard of except on Craftsman mowers. On Craftsman mowers it was fairly common. The issue was normally a bad equipment relay. There are typically 3 relays somewhere under the hood. One of those has most likely failed.

I don't remember whether the relay was wired into the ignition kill circuit or if it provided power to the Spark Advance Module. If it were wired to the kill circuit, it's job would be to unground the white kill wire from the Spark Advance Module. If it's wired in the power circuit, it would provide battery voltage to the Spark Advance Module.

Simply check the red wire going to the Spark Advance Module for battery voltage with the key in the on/run position and also while cranking the engine. If you have power, disconnect the white kill wire from the Spark Advance Module and see if spark comes back.

Could it be a Spark Advance Module or ignition module issue? Sure, but the failed relay was a much more common issue. And unfortunately, you can't just move the relays from one position to another. All 3 have to be working.

 

[VegetiveSteam]

This is from the Sear parts website. You can probably get a relay at a local parts store. Just make sure the terminals and in the same configuration and have the same numbers on each terminal.

 

[stonum]

Simply check the red wire going to the Spark Advance Module for battery voltage with the key in the on/run position and also while cranking the engine. If you have power, disconnect the white kill wire from the Spark Advance Module and see if spark comes back.

I tried your suggestion. The voltage is there with ignition on and cranking. No spark at plug with white wire disconnected. I got a feeling this is going to take a while to figure out.
Also, here's those 3 relays.

 

[stonum]

This is from the Sear parts website. You can probably get a relay at a local parts store. Just make sure the terminals and in the same configuration and have the same numbers on each terminal.

View attachment 68485

My next thing to try I think is to get new relays. I'm trying not to just give up on this mower, but it ran like a brand new one up till now.