20 hp Kohler command

[John2189 405]

Once in awhile it seems to just run on one cylinder for about 20-30 seconds then runs normal. I’ve pulled the choke when it happens and it doesn’t change, so I don’t think it is fuel related. 
when a coil goes bad, can it be erratic, or go bad right away.  
or mabe a bad spark plug?

[8ntruck 6,358]

Sounds like an ignition problem to me.  Fouled spark plug?  Bad coil?  Bad spark plug wire?

[RED-Z06 2,117]

Try new RC12YC plugs first, if it continues, may have to dig deeper into the ignition.  Do you see a black box on the cowling, little smaller than a deck of cards?

[John2189 405]

6 hours ago, RED-Z06 said:

Try new RC12YC plugs first, if it continues, may have to dig deeper into the ignition.  Do you see a black box on the cowling, little smaller than a deck of cards?

The plugs are new, don’t remember the number of them. But that doesn’t mean one could be bad.
It has the black plastic impulse fuel pump and the voltage regulator 

[John2189 405]

22 minutes ago, John2189 said:

The plugs are new, don’t remember the number of them. But that doesn’t mean one could be bad.
It has the black plastic impulse fuel pump and the voltage regulator 

Could the fuel pump be going bad? Earlier this summer, I replaced all the rubber hoses because they were hard. 

[RED-Z06 2,117]

1 hour ago, John2189 said:

The plugs are new, don’t remember the number of them. But that doesn’t mean one could be bad.
It has the black plastic impulse fuel pump and the voltage regulator 

So you dont see a module like this?

[John2189 405]

22 minutes ago, RED-Z06 said:

So you dont see a module like this?

No nothing like that. This is a Simplicity, not a Wheel Horse. 

[RED-Z06 2,117]

12 hours ago, John2189 said:

No nothing like that. This is a Simplicity, not a Wheel Horse. 

Its a Kohler Command...All Kohler Command Twins and Singles fot about a decade, used a SAM module that retarded timing for easier starting and ramped timing in as speed increased for more power.  When the SAM modules fail they cause timing to jump around and in some cases, because the coils were independently controlled, cause intermittent loss of spark...the fix was to replace the coils with the updated solid state coils and harness.  Here is the module on my 27hp Command on my Simplicity 

[John2189 405]

1 hour ago, RED-Z06 said:

Its a Kohler Command...All Kohler Command Twins and Singles fot about a decade, used a SAM module that retarded timing for easier starting and ramped timing in as speed increased for more power.  When the SAM modules fail they cause timing to jump around and in some cases, because the coils were independently controlled, cause intermittent loss of spark...the fix was to replace the coils with the updated solid state coils and harness.  Here is the module on my 27hp Command on my Simplicity 

Mine doesn’t have that box.  Its a 1996 Sunstar. The book says it has an electronic CD ignition system 

the model number for the motor is ch20

Edited September 16, 2022 by John2189

[John2189 405]

Put new plugs in and it still did it. Im guessing coils are next. 
 

I hate it when there is an intermittent problem. Id rather it go completely bad to make it easier to find 

[RED-Z06 2,117]

On 9/16/2022 at 1:00 PM, John2189 said:

Put new plugs in and it still did it. Im guessing coils are next. 
 

I hate it when there is an intermittent problem. Id rather it go completely bad to make it easier to find 

You can try to close the plug gaps some...this can mask a failing coil...if it stops then you know 

[John2189 405]

16 minutes ago, RED-Z06 said:

You can try to close the plug gaps some...this can mask a failing coil...if it stops then you know 

The plugs I took out only has 6 -10 hours on them and they look like new

[RED-Z06 2,117]

14 hours ago, John2189 said:

The plugs I took out only has 6 -10 hours on them and they look like new

Cool.  That has nothing to do with what i posted.  Closing the gap makes it easier to jump the gap, if the problem improves then you can safely say its a bad coil 

[John2189 405]

59 minutes ago, RED-Z06 said:

Cool.  That has nothing to do with what i posted.  Closing the gap makes it easier to jump the gap, if the problem improves then you can safely say its a bad coil 

Ok I just re read your post. Im at the beach right now. I’ll close the gap when I get home. 

[RED-Z06 2,117]

2 hours ago, John2189 said:

Ok I just re read your post. Im at the beach right now. I’ll close the gap when I get home. 

I had a briggs twin that would drop a lung under heavy load, perfect compression, new carb, no leaks...started fine and idled fine...turn on the deck and it would drop one side until it got back to full speed.  I closed the gaps to .020 from  .030 and while that did cost me some power...it no longer dropped a cylinder.  New coils fixed it

[John2189 405]

Thanks I’ll try it. The bad thing is I just had everything apart to put new head gaskets never thought ro look to see what it had for the ignition 

[Wild Bill 633 767]

On 9/15/2022 at 8:16 AM, John2189 said:

This is a Simplicity, not a Wheel Horse. 

FYI, simpletractors.com is the Simplicity & Allis Chalmers website.

The older Kohler Command ignition coils are known to go bad. The CH20-64512 replacement ignition coil is P/N 24 584 201-S, $54.78 each. 0.012" clearance gap.

[John2189 405]

5 hours ago, Wild Bill 633 said:

FYI, simpletractors.com is the Simplicity & Allis Chalmers website.

The older Kohler Command ignition coils are known to go bad. The CH20-64512 replacement ignition coil is P/N 24 584 201-S, $54.78 each. 0.012" clearance gap.

Thanks I’ve not heard of them, I’ll join that forum 

Edited September 23, 2022 by John2189

[John2189 405]

On 9/18/2022 at 1:29 PM, RED-Z06 said:

I had a briggs twin that would drop a lung under heavy load, perfect compression, new carb, no leaks...started fine and idled fine...turn on the deck and it would drop one side until it got back to full speed.  I closed the gaps to .020 from  .030 and while that did cost me some power...it no longer dropped a cylinder.  New coils fixed it

I closed the gap for the plugs from.030” to.020”. That didn’t help it.  Still does it and it takes it longer to recover.  I have new coils on order.

john