# Craftsman tractor stalls when brake is released (at high engine speed)



## cc-scott (Aug 29, 2010)

I got a wired problem with my craftsman mower. It will start fine and drive well for the first few minutes. Then it will stall unless I depress the brake or reduce the engine speed. 
To put it in another way, the moment I release the brake, it starts to run very rough and then stall. The only way to keep it from stalling (without depressing the brake) is to reduce the engine speed. (Seems cutting down the load?). 
Could it be the transmission? I tried changing transmission oil, but that did not help. 

Thank you for your ideas!


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## 30yearTech (Sep 14, 2006)

Could you post the model number of your unit? It should be located on a decal underneath the seat.


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## cc-scott (Aug 29, 2010)

Model No.
917.272247
Craftsman lawn tractor 20HP Kohler
automatic transmission.


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## cc-scott (Aug 29, 2010)

Forgot to mention. It is DLT2000.
Thanks 30yearTech


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## 30yearTech (Sep 14, 2006)

I don't think it's a transmission issue. It is more likely that when you release the clutch more load is applied to the engine and the additional load causes the engine to run erratically. I would first try a new spark plugs, making sure they have the correct gap. If this makes no difference, then you may have a fuel delivery issue as it also sounds like the engine may not be getting enough fuel. You could try applying a little more choke when the engine starts to stall to see if this helps any. If it does, then that's a good indication that the carburetor needs service.


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## cc-scott (Aug 29, 2010)

You are good 30yearTech! applying choke did stop it from stalling. In fact, even after closing choke, the engine still runs smoothly for a minute before it stalls again.
Do I still start from replacing the fuel filter or go directly to carb?
As for carb service, does it mean take it apart, clean and reassemble? (I am ignorant, but willing
Thank you!


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## 30yearTech (Sep 14, 2006)

I would replace the fuel filter for sure, but likely the carburetor needs to be taken apart and cleaned as there is probably something that is restricting fuel flow through the jet and nozzle into the engine.

You can download a service manual for your engine at the Kohler website

www.kohlerplus.com


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## cc-scott (Aug 29, 2010)

Thank you! I will give it a try and keep you updated...


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## cc-scott (Aug 29, 2010)

Now I tried with new fuel filter and cleaned up carburetor. Unfortunately it did not help. 
One piece of info I forgot to mention. The day when this symptom started, I was mowing heavy grass under hot weather, as well as hit a couple rocks along the way...
All this with a mice nest sitting on the engine block (I later found out and removed)

Could it be the engine was overheated and damaged?


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## cc-scott (Aug 29, 2010)

Just uploaded the video to youtube:


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## 30yearTech (Sep 14, 2006)

What are the spark plugs set at?

You may also want to disconnect the kill circuit on the engine from the rest of the tractor to see if that could be causing any issues as it kind of sounds like an ignition miss to me.
The white wire on the engine harness should be the one that kills the engine, if you remove it from the harness block you can test the operation of the engine without any of the safety switches, relays or ignition switches connected. Just keep in mind that the engine can only be killed by grounding the white wire to the engine case or frame, or by choking the engine down. If the carburetor has an after fire solenoid, it will still die when you turn the switch off, it will just be delayed a second or two.


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## cc-scott (Aug 29, 2010)

According to the manual, the spark plug (RC12YC) was gapped at 0.030''
(the new ones I bought was at 0.045'', I have to knock it down to 0.030'')


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## 30yearTech (Sep 14, 2006)

Then I would try disconnecting the kill switch and check to see if that makes any difference.


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## cc-scott (Aug 29, 2010)

Just tried and disconnecting the white wire worked! 
You the man, 30yearTech!
I guess I could just drive around with the white wire removed
Or else, how should I proceed to find the culprit?


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## 30yearTech (Sep 14, 2006)

It's one of the safety switches, and most likely the one under the seat. Try unplugging the connector from the seat switch and then have a look at the plug, in the middle of the plug between the two terminals openings there is a small button that pushes in when the plug is attached to the switch. Use a small probe to operate this button several times and then reattach to the switch. Plug the white wire back in and see if it will work now. These switches sometimes get some build up in them and sometimes will not "sense" that they are plugged in to the switch and can cause this problem. It's also possible that the switch itself is bad, but I find that about 90% of the time, it's the little sensor switch in the plug, and operating it a few times cleans it up.

Also note: If you leave the white wire disconnected, the engine will start with the mower blades on or transmission in gear and if you were to fall off the unit while mowing it would not stop. It would be best to repair it correctly so that all the safety components work properly.

Best of Luck....:thumbsup:


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## dj722000 (Oct 29, 2008)

Sounds like one of your safeties is going bad like 30yeartech describes up above. I would maybe suggest looking at your limit switch for your brake pedal or anything after that limit switch since your having problems when releasing the brake pedal. Just pull the harness from the limit switch and put a piece of wire in the harness where the limit switch would normally go. If it runs fine, then that is the problem, if not then its a different one. Which could be the seat, mower engagement, shifter. DO NOT keep them like that, it is only for testing purposes. When you find the problem, replace the switch.


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## cc-scott (Aug 29, 2010)

I tried the switch under the seat, but it did not seem to help. Actually even if I did not sit on the seat, the mower would still run. 
Will try the limit switch tomorrow. Is there a diagram that shows where all these safety switches are? 
Thank you guys!


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## 30yearTech (Sep 14, 2006)

cc-scott said:


> I tried the switch under the seat, but it did not seem to help. Actually even if I did not sit on the seat, the mower would still run.
> Will try the limit switch tomorrow. Is there a diagram that shows where all these safety switches are?
> Thank you guys!


I am not talking about the switch under the seat, but the switch inside the plug that attaches to the seat switch.


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## cc-scott (Aug 29, 2010)

I assume the plug is the green one shown below. There are two metal contacts, but nothing in between for me to press...


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## 30yearTech (Sep 14, 2006)

You are correct. It looks like the switch has been removed. Simply test it with this unplugged and see if it makes a difference. If it does then you should test the switch itself. I would start with the seat switch, simply because it's easier to access, and then the one on the clutch/brake pedal. The other switch should be located on tractor frame usually on the side near the pedal under the dash panel, on some they may be on the underneath side of the frame.


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## cc-scott (Aug 29, 2010)

The only switches I can locate are relay assembly (109748X) and interlock switch (part no: 176138). Are these what you were talking about I should test? How do I test them? for example, relay assembly has five holes, which ones should I connect with a wire?

Now with kill switch (white wires) disconnected from the engine, the machine runs but mower (PTO) won't turn on, is this normal? I thought it would run, just not having any of the safety features.

Thank you,


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## 30yearTech (Sep 14, 2006)

If the only wire unplugged is the white kill switch wire, then there should be no reason for the PTO not to work. If the entire plug assembly with power wires is disconnected, then this could cause an issue with the PTO. Interlock switch you referenced is the other switch that is activated by the clutch / brake pedal. It's possible that the relay could be causing the problem as well. The relay is a standard automotive type relay, you can pick one up at an auto parts store.


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## cc-scott (Aug 29, 2010)

How about the relay assembly, maybe it is not activated by clutch pedal and I should not worry about it, but rather go straight to replace the interlock switch?
I also had a chance to use a ohm meter to test the seat safety switch. Interestingly, no matter the button is depressed or not (whether the seat is occupied or not), resistance between the two plugs are always zero. At least this should not cause much problem rather than bypassed seat safety switch, right?

The fact PTO did not engage with only kill switch removed might be the new main drive belt I put in this afternoon, I will double check tomorrow.

Thank you for offering this much help, 30yearTech!


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## 30yearTech (Sep 14, 2006)

I am not sure on your model, but on many the relay is operated by both the interlock switch and the PTO switch to kill the engine in the event the operator leaves the seat. Since the seat switch is not completing any circuit then it's doubtful that either one of the other switches should affect the running of the engine, since they both travel through the seat switch.

On units that use a relay they sometimes use a normally open switch on the seat, this means it must complete the circuit when operated. When the switch is operated the circuit is completed and the relay is energized. I just looked up the seat switch and on your mower it shows to be normally open, this means that it should make a connection when someone is seated in the seat. Try a jumper wire between the terminals of the plug and see if it will work this way. This may be why there was no micro switch in the plug, as unplugging the switch will prevent the unit from being used. If a jumper wire takes care of the issue, then the seat switch needs to be replaced.


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## cc-scott (Aug 29, 2010)

If seat switch is always closed (zero resistance between the two plugs of switch) no matter depressed or not, then the seat switch is acting as a jumper wire for the two terminals all the time, right?


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## 30yearTech (Sep 14, 2006)

cc-scott said:


> If seat switch is always closed (zero resistance between the two plugs of switch) no matter depressed or not, then the seat switch is acting as a jumper wire for the two terminals all the time, right?


Your right, sometimes I should go back and read the post before replying. I thought you said it had no reading, not zero resistance. I would still try a jumper, as sometimes these switches have what I call a "sweet spot" where the switch just does not work right. Jumping the switch will eliminate this as a possibility.


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## cc-scott (Aug 29, 2010)

Sounds good, I will give it a try after work today.


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## cc-scott (Aug 29, 2010)

Things are getting more interesting...
Since the lawn hasn't been cut for more than a month , I tried to mow with kill switch unplugged. Like I said last time PTO did not engage. This time, I noticed that the PTO will only engage when the tractor is in near perfect level condition. Any deviation will shut off the PTO. Although, after running the mower for a while, it seems to become less sensitive. What is behind all this, what will make PTO so sensitive to the levelness of tractor?
Thanks,


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## 30yearTech (Sep 14, 2006)

Perhaps a bare wire somewhere that may be grounding out when the frame is not level, or possibly something loose in the relay assembly. As far as I know this unit does not have any type of tilt switch to shut the unit down.


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## cc-scott (Aug 29, 2010)

Finally nailed it. It is one loose screw that connects the grounding cable to the frame right above transmission. This one loose screw caused all the problems I mentioned above, engine misses at high speed; PTO won't engage unless frame is bended certain way.
I can't believe it is such a simple problem which lead me to change transmission fluid, fuel filter, spark plugs, carb work, air filter... 
I guess now my machine is well serviced
Thank you 30yearTech for offering very helpful suggestions along the way. Quite a learning for me.


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## 30yearTech (Sep 14, 2006)

Congrats on getting it figured out. Perseverance is sometimes the key to figuring these things out. Glad it all worked out.


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