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Discussion Starter #1
Hey all, first post, but been on several different forums for my cars.

I have a question for you gurus and I know you have an answer!

At the house we own an older JD F935 72" mower. I believe it has the yanmar diesel in it (only from what I have read), but a diesel nonetheless! The issue has to do with the PTO and throttle...

-When starting the mower, it won't turn over, I have to put my foot on the blade disengage (big red pedal) and push about 2" down to get it to start. Once I let go of it, the mower will die on its own.

-while keeping my foot in the red pedal, if I hit forward or reverse more than 1/8 throttle, it will die. Less than that I can limp it along.

-While running, if I engage the PTO, it will die immediately.

It will idle up to full throttle just fine, No issues getting fuel, so I ruled that out. Doing some poking around, I read that the brake switch under the foot area can go bad? Could someone explain that further? I would assume to replace it I need to drill out the 2 rivets that holds it on. If that is even the issue.

I should add we have mowed with it 4 times this year already, the last being 5 days ago and it ran fine with absolutely no issues. At wits end trying to figure out.

If more information it's needed just let me know, I will supply what I know.

Serial number: CP22-61-4287
Model: 3TNA72UJ

Thanks all.

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No you are in the right section, just not a lot of people with those older front deck mowers. I have a F932, the gas version of the F935.

There is a switch in the bottom of the seat. I would try jumpering/bypassing it first. I suspect its going bad and when you push on the brake that maybe you are putting just a bit of extra pressure on the switch making it contact. Jumper it out to start with to eliminate it all together as a possibility.


If you still have an issue then check the brake band that goes around the PTO shaft(under the seat) there is a switch in there that kicks out the clutch when you step on the red pedal. Also check the PTO switch itself, if it was stuck in the closed position this could cause a no start as well.


My bet is on the seat switch.
 

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Discussion Starter #4
I gotcha, figured since they run forever, someone would have gotten it quicker, looks like a pretty active forum which is good to see. FB isn't taking over here as well...

So it turns out, dad ran a jumper to bypass the seat switch as you stated. That was years ago, and I guess it finally corroded to the point is was just shorting it out. He called the local mower place and they said the same exact thing you stated.

Problem is solved and I'll be mowing today before the rain hits!

Thanks again.

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