Ask Me Help Desk - MTD 42 inch Yard Machine Engine with PTO engaged

I have a 42 inch MTD Yard Machine lawn tractor. This is the 3rd season for this mower. Sunday I was cutting the grass as usual, everything was normal when the engine began to miss out and sputter, it sounded like it was going to backfire. It acted like it was running out of gas. I pulled over by the shed to get the gas can. When I lifted the cowling the tank was half full. I changed the fuel filter even though the gas was flowing freely through it, put a new spark plug in, and changed the air filter, all to no avail. As I tried different things, changing throttle speeds, choking the engine etc. I soon realized that the engine appears to run completely smooth until I engage the PTO, then the problem starts again. I made sure the deck and pulleys were clean and turning freely but as soon as I engage the cutting mechanism the engine begins to fowl. Do I have internal problems like burnt valves or bad rings that show up when the strain of the cutting unit engaged or is it possible that one of the safety switches is shorting out when the PTO is engaged. Thanks for any help I can get. Although the cutting season is about done, we have 30 trees on our property and I use the mower to chop up leaves and bag them 3 or 4 times a week in the fall. Rick

Hi,
Best guess is problems with the seat switch or the wires leading to it. It is supposed to cut off if the seat is unoccupied and the PTO is on. Unless it has two circuits it is a bit surprising that it does not act up with the brake/clutch.
Peace,
Clarke

Hi! bounder900, and welcome to AMHD. Also, A big Howdy! To you Clarke! :)

I think you hit the bullseye, Clarke.

I was having the same problem when I would engage the mower deck drive, I had the brake/clutch in.
The engine would die when I went to engage, but come back to life if I returned to the disengage stop on the dash. :confused:
Never did try with the because out, and the trans in neutral.

Pausing to think a moment... :rolleyes:... I've learned, anytime the engine:
A) Won't start or B) acts up while running, it's always that darn seat switch or something to do with it.

Check the rear fender, under where the bolt studs that hold the switch mounting bracket on...
While standing behind your tractor use you hand to lower the seat.
If you see shiny spots on the rear fender directly in line with the studs, then there's also a good chance the engine is being grounded out.

What's happening is; over the years the seat springs get weak, and when you sit down on the seat those studs will scrape away the paint, grounding the engine out. My LT has three interlocks, and I didn't want to spend the time to trace where the ground was going, so I just duct taped over the shiny spots.

It would be better though, if you used something like Specialty Coatings & Adhesives, Industrial Coatings, Protective Coatings – Plasti Dip International to coat the nuts, and studs that hold the switch cover on, or epoxy a leather/plastic/rubber pad where it hits.

You can try new springs, stretching the old, or do like I did, and borrow a tip from NASCAR... Add spring rubbers to decrease the spring rate.
I made mine outta' extra brake adjustment slot covers for my old truck, that I had lying in my parts bin, just epoxied 'em in.
It makes for a bit rougher ride, but I don't have that "Ghost-mon of the Tractor" :eek: trying to shut me down every time I lean over or lift a cheek. :D

K

Thanks for the help. The configuration is different than described and I diabled the switch designed to keep the mower from cutting in reverse, which may explain the clutch issue, but the culprit was the spring conact. Where the springs made contact with the seat, the paint was scratched off. I covered these areas with duct tape and the problem was solved. Thanks again

Quote:

Originally Posted by bounder900

Thanks for the help.

Your welcome!

Quote:

Originally Posted by bounder900

The configuration is different than described and I diabled the switch designed to keep the mower from cutting in reverse, which may explain the clutch issue,

So far I haven't been the "proud owner" of one of those. :rolleyes: (short rant).......Now who backs their tractors without looking? Next thing you know the feds won't allow text-ing on your cell phone while cutting the lawn... okay... I'm done, I'll put my soapbox away.

Quote:

Originally Posted by bounder900

but the culprit was the spring conact. Where the springs made contact with the seat, the paint was scratched off. I covered these areas with duct tape and the problem was solved. Thanks again

Wonderful! I wonder what Redgreen would think 'bout usin' it for that.

K