john deere stx38 pto intermittent

knyriJuly 24, 2010

Recently bought a JD STX38 yellow deck. First mowing was beautiful until the end when the PTO suddenly cut out. I flipped the PTO switch off and on several times and nothing happened.

When I vary the throttle it will sometimes engage, usually above half throttle. When I move the throttle afterwards it sometimes stays engaged and sometimes does not. However it will always disengage after a few feet of cutting grass.

With the engine off and the in the "on" position I turned on the PTO and did hear a click.

There is a black and yellow wire two pronged male connector not connected to anything near the starter. I cannot find an uncoupled female connector for it.

What I have done:

- Checked the belts. They are tight and on track

- Cleared excess clippings from the deck, blades, and engine

- Searched this and other sites for similar cases. Found none that match

It did not come with any manuals. I would appreciate any sent to me.

I am new to riding mowers but have moderate experience tinkering with push mowers.

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I am getting the impression that you are not running the engine near its maximum throttle position. You need to run the engine nearly full throttle at all times when you are mowing for a number of reasons.
Running the engine near full throttle gets the maximum output of current from the engine alternator, and you need that to ensure there is enough voltage to keep the PTO clutch engaged.
What you have described sounds very much like the battery became so weak that it could not keep the PTO clutch engaged by the time you got near the finish line of your mowing.

    Bookmark   July 24, 2010 at 11:04PM
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Always listen to mownie, and I agree with his assessment.

Charge your battery, and check the electrical connections, paying particular attention to the battery cables - both of them. Also take a look at all the wiring and connections that feed the PTO, as well as the engine ground wire. Intermittent problems frequently result from corroded connections and/or frayed wires.

Among the reasons to run at full throttle include battery-charging, as mownie mentioned, blade speed, and ensuring good oil flow. Your Kohler engine has an oil pump, but some engines are splash lubed, which makes high engine speed even more important. As a general rule, virtually all small engines should normally be operated at (or very near) full throttle.

Post back if these suggestions don't fix your problem; there are a number of possibilities.

    Bookmark   July 25, 2010 at 11:27AM
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I always keep it at full when mowing. The varying was just a random idea that popped into my head.
From the tinkering I was able to do today, it looks like the ground bolt came loose.

Found to be very helpful.

    Bookmark   July 27, 2010 at 6:36PM
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