[churley79]

Looking for help with my old John Deere. It's a 1981 111, but I had the engine swapped with a 14 HP engine. The mower, when running, runs like a champ. However, here lately I've been having a problem that when I engage the PTO it either sputters/backfires or just shuts down completely, if I flip the PTO switch off fast enough, the engine stays running. I took the battery up to Advance Auto and they ran a diagnostic test on it and said the battery was fine, just weak. So I currently have it on the charger and have let it charge over night. So, I guess my questions are: would a weak battery cause this? Or, is there some other problem that I am missing? A guy here at work said possible the spark plug needs replaced. (That's only a 5 dollar fix, so hoping for that) :i_praying

Thanks in advance.

Collin

 

[k91]

Are you sure the charging system is working? An electric PTO will need 12V to operate so a weak battery isn't going to work. The PTO may need adjusted as well if it is adjustable on the 111 which I do not know.

 

[John Deere Fan]

Do you engage the mower at half throttle or so? It is hard on the PTO/engine to get the blades spinning when the engine is at full throttle.

 

[Larry from MT]

I've got a 1981 111 also (this one).

I'd try a new battery first --- but ---

My 111 didn't come with a electronic ignition --- I changed that out years ago when it started to give me trouble (starting). This could be another symptom.

Always kick in the electric PTO at a slow engine speed --- But quite a bit above idle.

 

[churley79]

Yeah, I think I am going to try a new battery. Even though the one I have is not even a year old, but I've had problems with it from day 1. First of all, it was the cheapest I could find at the time, it is an Autocraft 160CCA battery. I'm thinking I may just go ahead and bite the bullet and get a 340CCA Die Hard. I don't know if the higher CCA will make any difference or not, but it's worth a shot.

 

[Larry from MT]

For what it's worth --- I only buy the cheap 160CCA batteries because the expensive ones I bought didn't last any longer --- 2 years either way; even if I put them in the basement over the Winter.

My 160s work great though ----- for 2 years.:goodl:

 

[churley79]

Ok, so replaced the battery, still doing the same thing. However, I did find a little extra bit of information that may help out.

When I flipped the PTO switch, while it was sputtering to a stop I pressed the brake and it fired back up and ran fine. Then I pressed the brake and could ride around with the PTO on and the blades spinning. Any ideas? Help. Please.

 

[arniearni]

I think you have a seat switch problem. The seat switch wire runs through the pto switch (white wire). I don't know how that would tie in to the brake pedal though but that's where I would start. The seat switch I believe is open when you are sitting on the seat. When you get off the seat the switch closes and the white wire is shorted to ground. If the pto switch is in the on position the shorted white wire connects to the ignition and kills the engine so I would look to see if the seat switch opens when it is pressed(or sitting in the seat). At least I believe that is how the 111 is wired.

 

[churley79]

So, doing a bit of digging last night, I guess the easiest way to bypass it is to cut the two wires coming to the seat switch (one coming from underneath the body and another grounded on the steel seat spring) and splice them together, right?

Would be nice to know how/why the pto, seat switch and brake pedal all affect each other. Could anyone explain?

 

[Larry from MT]

So, doing a bit of digging last night, I guess the easiest way to bypass it is to cut the two wires coming to the seat switch (one coming from underneath the body and another grounded on the steel seat spring) and splice them together, right?

Would be nice to know how/why the pto, seat switch and brake pedal all affect each other. Could anyone explain?

Check and see if the electric wires running from your PTO to the switch are somehow contacting the brake pedal underneath the deck. They ARE in the same area. Maybe a loose connection or a short that hitting the brake temporarily straightens out.

 

[revil41]

Same thing happened to me the carb worked its way loose, check that its tight, to much air will make it sputter and choke itself out.

 

[churley79]

Got it fixed. It was the seat switch. However, I was duped by the lawnmower. I thought it was a normally open connection that when you sat on the seat it closed the circuit. So, I spliced the 2 wires (so it went straight to ground) and tried to engage the PTO, it died.

So, heeding the advice of Larry from MT, I took off the deck, looked around and traced all the cables to see if I saw any bare copper or anything touching something it didn't need to be. Didn't see anything.

On a whim, I disconnected the ground and VOILA, the pto engaged. Come to find out, it's a normally closed connection, so when you sit on the seat it breaks the connection going to the ground.

So, all in all, what should've been a 15 min fix took me over a couple hours. But, hey, you live, you learn, you move on. At least it's working.

 

[Larry from MT]

Glad you got it fixed ---- We've gotta keep those 111s runnin'!:thThumbsU