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Mark Dotson
Mark Dotson,
Category: Small Engine
Satisfied Customers: 10
Experience:  Master Service Technician at Mark The Mechanic
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Mower engine stops when engaging clutch, Craftsman 18 hp

Customer Question

Mower engine stops when engaging clutch
JA: What's the make and model of the mower? And can you guesstimate how old it is?
Customer: Craftsman 18 hp model###-##-####JA: Do you plan on doing the work yourself?
Customer: if possible
JA: Anything else we should know to help you best?
Customer: this is main problem, engine runs fine otherwise
Submitted: 9 months ago.
Category: Small Engine
Expert:  Mark Dotson replied 9 months ago.

Hi, my name is***** and am happy to assist with the problem you are having. I am sorry to hear about the problem you are having with your machine.

I have a couple questions to help make sure that I understand the problem correctly.

Does your mower have a PTO clutch that engages the blades or do you have to use a handle to engage them?

Does the mower die immediately or does it bog down and then die?

Customer: replied 9 months ago.
It has a handle for manual engagement. The engine dies soon after either the clutch or mower is engaged. If the clutch pushed back in quickly, the engine resumes running. While I was waiting for an answer, I repeated the "in-out" (engage-disengage) several times while in either a forward or reverse hear and finally the mower remained running while in gear and/or with blades in gear. I finished a large area of lawn. But I know that likely tomorrow I will go through this situation again.
Expert:  Mark Dotson replied 9 months ago.

Thank you for the updated information. Now I more fully understand the situation. It appears that there is a safety switch that is malfunctioning in the system. There are normally 3 of them. One for the seat, one for the clutch pedal and one for the lever than engages the blades.

The first test I like to do is eliminate the seat switch by starting the mower and raising up off the seat and seeing if the engine dies. On most mowers, it will die with the engine running and the blades not turned on. Then shutting it off and unplugging it and then testing the mower again.

I have a suspicion that your clutch switch is probably the culprit here. You can remove it and do an continuity test. With the switch button extended, check for continuity across two of the contacts. Then push the button in and check for the same on the other two contacts.

A bad safety switch will cause the problem you are experiencing and will immediately kill the engine by grounding it out.

If this concludes our troubleshooting, please rate my response. If you have any further questions, don't hesitate to ask. My goal is to do my best to help you remedy your small engine problem and continue to keep my high rating as a Technician.