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JohnF2015, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1132
Experience:  Owner/Service Technician at S & J Small Engines
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Craftsman riding mower with Kohler engine model # SV735S.

Customer Question

Craftsman riding mower with Kohler engine model # SV735S.
When mowing for about 15 minutes the motor will drop down to about 1/2 throttle, keeps running for about one minute and then bam right back to full throttle, again in about 15 minutes it is back down one or two minutes and back up to full throttle. I have tried moving the throttle up and down but no change, turned off the mower, no change.
Can you give me a clue as what to look at.
Thanks, Syd
Submitted: 1 year ago.
Category: Small Engine
Expert:  Curtis B. replied 1 year ago.

If you cut off the electric clutch will it recover?

Expert:  Curtis B. replied 1 year ago.

Sorry, you said you did that! Ok, My thought is the electric fuel solenoid in the carburetor is getting hot. It plugs the main jet in the carburetor when it closes. If it is trying to close, engine looses fuel. Usualy t will recover if you turn engine off and restart. You say this one does not?

Customer: replied 1 year ago.
One, What are you talking about, I do not have an electric clutch.Two, Sorry I did what.
Three, When did I say if I turn the engine off and restart it would not correct.
SydP.S. No phone calls or any more advice.
Expert:  JohnF2015 replied 1 year ago.

Hi, my name is***** will be assisting you.

I noticed that your question has not been fully addressed and wondered if you still needed assistance.

The first thing that I would look at is the ignition system, it sounds like you are loosing spark on one cylinder which would explain the loss of power and rpm. This engine has two ignition coils on it, one for each cylinder therefore you could be loosing spark on one cylinder and the other continue to run just fine. This would be the first thing that I would look at based on your explanation of the problem. I have seen the coils be working good and then quit firing for a short time and then start working good again. The only real way to test this is with a in line spark tester attached between the spark plug wire and the spark plug itself, you can then watch the spark when the machine is acting up or not running properly. It will be easier if you have two testers so you can check both coils at the same time but it can be done with one.

Thank you it has been a pleasure to assist you.

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