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My Bolens ST120 (3212G) with a Briggs and Stratton 12 HP would not start this spring, and additionally had a batttery draw, so I had a new stator and resistor installed by my local small engine repair garage for $160. Now a new frustrating problem has arisen. it is somewhat intermittant, and therefore is driving me nuts.

When I got it home, started up beautifully, and backed her off the trailer. I switched on the PTO enagaging the blades, and VROOM, I was mowing. For about 30 feet. Then she began to stall. I put my foot on the brake/clutch, and it came back to life. Now when i start it, it stalls when i back my foot off the clutch pedal. I've tried every combo of in gear, out of gear, PTO on, PTO off, etc, etc.

Here's where it gets INTERESTING and confusing at the same time: I noticed this round rubber grommet on the deck that IS DEPRESSED WHEN YOU HOLD DOWN THE CLUTCH. (see pics) I figured maybe I could bypass the clutch JUST TO TROUBLESHOOT - NOT FOR PERMANANT. underneath, it has 3 wire leads coming from it. One large one in the middle, and two smaller ones on either side. I unhooked the middle one, and VOILA, it ran again WITH MY FOOT OFF THE CLUTCH - for 2 rows of 40 feet. Now, same problem - back off the clutch - in gear or not, PTO engaged or not, and it stalls dead - just like a dead man switch. Could it be the repair man crossed a wire or what? This is frustrating - i prefer the PTSD!! In short it starts and runs great, as long as I leave my foot ON that clutch pedal. If not - stall. I sure could use some advice. I'd like to have some info to bring in with me. I can't afford them blindly searching on a disability pension.

UPDATE: WEIRD TO WEIRDER, BUT IT MIGHT HELP: As i was sitting on this thing trying to figure this out, I noticed when i adjusted my ***** in the seat, it affected the aperformance. i noticed that the safety switch undert he seat would make the engine stall when DEPRESSED - WHICH IS OPPOSITE OF HOW IT'S SUPPOSED TO WORK. So I disconnected the leads, and it ran fine for a good long while. Not perfect - it sputtered and spat, but ran definately better. Could there be some sort of connection between th wires for the seat safety switch and the wores under the rubber grommet switch i described under the clutch pedal? MY GOD HELP!!

sounds like either the clutch safety switch or the seat switch and if i was a betting man i would guess the seat switch if it has one

Definitely the seat safety switch. Look under the seat and you will either see a small push button switch on the chassis or wires going to the underside if the seat. This switch is a normally open switch which must be pushed in by your body weight to allow the PTO to work properly.

Rivets said:

Definitely the seat safety switch. Look under the seat and you will either see a small push button switch on the chassis or wires going to the underside if the seat. This switch is a normally open switch which must be pushed in by your body weight to allow the PTO to work properly.

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(not sure how this works, but will send this as a private msg as well as replying in thread - I'm kinda new at this)

I ended up pulling BOTH leads of the safe switch under the seat, and you are right, it did seem to run better. As I said, it sputtered and spat, but it ran better. I am confused by the following though:

1. Before I pulled the leads to the seat safe switch, they were firmly in place, and have never been an issue before.
2. Although it ran better, it only ran a BIT better - not markedly so. At least it didn't stall.
3. AND MOST IMPORTANTLY: When I first got it home, it DID run for 30 feet or so before it stalled. When i put my foot BACK ON THE CLUTCH it revved righ back up. WHAT WOULD ME PUTTING MY FOOT BACK ON THE CLUTCH have to do with the seat switch.
4. MOST CONFUSINGLY: This issue happened whether OR NOT the PTO was engaged! THE PTO had no change, on or off, as to this problem!

As it is, I have the leads to the seat switch disconnected. There are 3 leads under there, and only two - the two outer ones - were in use. the middle lead wasn't in use and there doesn't seem to be any wire for it in the harnes anywhere.

Any other thoughts?

An Appreciative Jim, Remer MN

The seat switch tells the engine someone is there. You can override the seat switch by locking the parking brake (clutch) in place. This is how techs can work on a unit without seating in the seat.

For diagnosis purposes only try running a jump wire between the two outside wires on the plug and see if it runs smoother.

ACHTUNG said:

(not sure how this works, but will send this as a private msg as well as replying in thread - I'm kinda new at this)

I ended up pulling BOTH leads of the safe switch under the seat, and you are right, it did seem to run better. As I said, it sputtered and spat, but it ran better. I am confused by the following though:

1. Before I pulled the leads to the seat safe switch, they were firmly in place, and have never been an issue before.
2. Although it ran better, it only ran a BIT better - not markedly so. At least it didn't stall.
3. AND MOST IMPORTANTLY: When I first got it home, it DID run for 30 feet or so before it stalled. When i put my foot BACK ON THE CLUTCH it revved righ back up. WHAT WOULD ME PUTTING MY FOOT BACK ON THE CLUTCH have to do with the seat switch.
4. MOST CONFUSINGLY: This issue happened whether OR NOT the PTO was engaged! THE PTO had no change, on or off, as to this problem!

As it is, I have the leads to the seat switch disconnected. There are 3 leads under there, and only two - the two outer ones - were in use. the middle lead wasn't in use and there doesn't seem to be any wire for it in the harnes anywhere.

Any other thoughts?

An Appreciative Jim, Remer MN

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Ok, that helps a bit. Now i see how they're related. As I said, there were 3 leads coming off the bottom of the seat switch, a center one that wasn't being used, and two outer ones with were. When I noticed my Butt was affecting the whole thing, I just disconnected (pulled off) the two leads. I thought I'd have to "Jump" them, but surprisingly I didn't. Next question is this: there isn't much to go terribly wrong with a seat safety switch, and it was never a problem before, so my next question - and you are being a saint here with your patience - should I re-attach the seat safety leads and look for a wiring problem elsewhere? And if so, where? OR...as long as she's running, should I leave well enough alone?

Rivets said:

For diagnosis purposes only try running a jump wire between the two outside wires on the plug and see if it runs smoother.

Click to expand...

Between what plug? the one under the clutch pedal or the safety switch under the seat?

Rivets said:

For diagnosis purposes only try running a jump wire between the two outside wires on the plug and see if it runs smoother.

Click to expand...

just to elaborate a bit more - I was confused because under the clutch pedal there are three leads and 3 wires in use. As I previosly stated unplugging the center one helped for about two minutes, so I reattached it. NOW...under the seat, there are 3 leads, but only two wires, and when i unplugged them, with the idea of just jumping them, turns out it ran better without even jumping them.

i am wondering if, in the spirit of doing it right, I should reattatch the two seat safety wires and search for a wiring issue elsewhere?

This is so confusing because before this spring's stator/resistor fix, this was never a problem!!!

Ok let's start over, because I am just as confused. First I am going to explain how everything should work. To start an engine you must be sitting on the seat (seat safety switch) and either have unit in park or foot on the brake/clutch petal (clutch safety switch). As I said before, you can override the seat with the parking brake engaged. After the engine starts you must be on the seat to engage the PTO. if the engine cuts out when the PTO is engaged, the unit thinks no one is in the seat.
Second, I don't know what resistor they fixed. Are you sure that they did not replace the stator and the diode? If they did replace a resistor, can you explain where it was?
If everything worked fine before the repair, we should really start there with everything hooked up the way you found it, and then start from there.

Rivets said:

Ok let's start over, because I am just as confused. First I am going to explain how everything should work. To start an engine you must be sitting on the seat (seat safety switch) and either have unit in park or foot on the brake/clutch petal (clutch safety switch). As I said before, you can override the seat with the parking brake engaged. After the engine starts you must be on the seat to engage the PTO. if the engine cuts out when the PTO is engaged, the unit thinks no one is in the seat.
Second, I don't know what resistor they fixed. Are you sure that they did not replace the stator and the diode? If they did replace a resistor, can you explain where it was?
If everything worked fine before the repair, we should really start there with everything hooked up the way you found it, and then start from there.

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First, do you prefer I send you private msgs, or just on thre thread? i'm afraid you won't see them of you don't go back to the thread!

OK To start over, I know there is a plunger switch under the the seat, i know it's function - i have had many mowers and am VERY familiar with its presence and it's concept. Last year, the mower worked fine until fall, when it became diffcult to start, etc.

This spring, I brought it in, and the stator and (i thought they said ) resistor was diagnosed as bad, so the repair was done. He said he tested it, indeed there was new grass on it, so I believe him. I got it home, it ran fine for 30 feet or so. i then noticed that as soon as it began to stall, it I quickly put my foot on the clutch, it sputtered back to life. i unhooked the center lead from the harness under the clutch as a troubleshooting beginning point, and it helped, but only for another 30 feet, so THAT clearly wasn't the problem. I THEN noticed that adjusting my rear on the seat was affecting the performance, so I had it in mind to disconnect the two leads on the seat safety switch and JUMP THEM - thereby bypassing and eliminating the safety switch under the seat as a troubleshooting technique. My plan was to see if this did the trick and if so, i'd just leave it "jumped" or replace the seat switch.

As it turns out, the two wire leads didn't need to be "jumped". As soon as I unhooked them, the mower now mows when i remove my foot from the clutch - with the two wires from the seat safety switch UNJUMPED and just hanging there loose.. i now suspect that since a tech can work on the mower by 'Locking" the clutch, there must be a wiring issue between the seat safety switch and the clutch locking switch.

I just dug out and consulted my receipt..indeed it says "resistor...$15.00". So we know it was a resistor.

I am just confused why it ran for him at the shop - I DO live down a 3.5 mile bumpy logging road so something may have jogged loose, but that's what the receipt indicates. i am frustrated because before taking a shot to the head in the military, and even since, i am known as the family fix-it guy. I can fix anything from indoor plumbing, wiring, boat motors, lawn mowers, cars...you name it. THIS wiring problem has me flummuxed (a minnesota word) and as I said - my military pension isn't enough to go buy a new cadet!

To tired to read your post but I have a parts donor at my shop that we just took an engine out . Scrap man will come for it soon ...

I am starting to understand some things and will get back to you tonight after work. Could you call your repair shop and ask them if it was a resistor or diode that was replaced. I know where the diode is and if that was replaced it should have nothing to do with your problem. The diode is part of the charging circuit. If it is a resistor, have them explain where it is located, so I can figure out what it does. Also you do not have to send a PM and a new posting each time. I try to reply to each posting as soon as I can.

Rivets said:

I am starting to understand some things and will get back to you tonight after work. Could you call your repair shop and ask them if it was a resistor or diode that was replaced. I know where the diode is and if that was replaced it should have nothing to do with your problem. The diode is part of the charging circuit. If it is a resistor, have them explain where it is located, so I can figure out what it does. Also you do not have to send a PM and a new posting each time. I try to reply to each posting as soon as I can.

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Sorry. I wasn't sure you would be notified if I just responded to a thread. If I respond to a thread like this, do you get notified? ANYWAY: I called the repair shop and asked for clarification on the resistor/diode issue. he said, and i quote "I don't know what the hell it's called. It sits behind the batter and is like a little plug. I wasn't sure if it was bad but they're cheap so I replaced it, and when i did it started right up"

I am beginning to think this whole thing is just a problel with the safety switch 'neath the seat. As soon as I troubleshooted and unplugged them, it ran fine - so I am going with that unless you say differently...

ACHTUNG said:

...
...If I respond to a thread like this, do you get notified?
... "I don't know what the hell it's called. ... I wasn't sure if it was bad but they're cheap so I replaced it, and when i did it started right up"

...

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When you respond to any thread, you will be 'subscribed' to that thread and they will automatically show when you are signed in ...Anything with any new activity will show in bold print...

A repair shop that replaces things that they Don't Know what it is called... ? I sure would Never trust. As Rivets said, I can't place any Resistor in that circuit... As for it being "cheap".. at $15 a pop for an unknown part, that may have something to do wit something, sounds like nothing was done so there was some bill padding ...
Finding an intermittent fault in an electrical circuit Can be done... & you don't fix it by throwing parts at the problem hoping you'll get lucky... You need to ask for a refund $$ and then get a different repair shop... Someone that will Know how to trouble shoot AND Know what a replaced component is called & what it's function is in a circuit...
:smile:KennyV

Kenny is right, get a refund ASAP and if we can't help you I'll help find a good repair shop. I think what they called a resister is probably a fuse from the description you are posting. I would also question replacing stator, as the stator does not have anything to do with not starting, it is for charging the battery. Ask for both the "resister" and the "stator" back, especially if they refuse any refunds on any of the parts. There are a few of us that would like to see them and tell you how to test them. Time to treat them like a hunger dog if you know what I mean.

If it is a fuse that was replaced, then we still have to find out why it blew in the first place. You say you can mow with it now, so let's leave it at that until we find out what your repair shop has to say. Just remember that you have disabled one of the safety switches. Can you post the model and serial numbers for both the tractor and the engine. This will allow us to see if we can find a wiring diagram and start looking for solutions to solve your problems.