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Discussion Starter · #1 ·
My Cub GT2523 Kohler Command 23 shuts down after about 15 minutes of mowing. After it sits for awhile (i assume cools downs it starts and goes again for about 10 minutes and shuts down and so on.
I have changed he rectifier, fuel pump/line and filter. I've drilled a hole through the gas cap vent so tank is well vented. I changed the oil and filter 2 days ago and tonight I disconnected the oil pressure safety switch. No improvement. Tonight after it stopping with the oil pressure switch I made it a point to check the fuel filter and it was visibly 3/4 full of fuel.
I'm out of ideas.
Thanks in advance:)
 

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I think what I would do if it's that consistent shutting off is take air filter off, have a can of starting fluid with you (WD-40 works & safer), as it starts to shut off spray into inlet.
Verify if it's losing fuel. If so it could be carburetor problems.
It doesn't sound like losing spark issue, but when it cuts off see if it's getting spark.
In line testers light with spark, less than $8.
20210610_214309.jpg


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'81 Gravely tractor, 50's 60's 70's 80's 90's Gravely tractors Various Honda Power equipment
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That will show its getting some power to the plug, but it might not be enough to jump the gap under compression, which is harder to jump then than it would be when not under compression.
You could have a ignition coil that is beginning to fail but putting out enough to show the spark in that tester, but not enough to actually jump the gap of the spark plug while it is in the engine under compression.
The coils fail when hot due to the windings expand an cause an 'Open' circuit, meaning the circuit breaks and will not complete the flow of electrons, or it is beginning to 'Short' the windings together from insulation break-down, then it won't create enough voltage to jump the plug gap under compression and ignite the fuel causing it to stop running until it cools down and the windings come back 'Together' to complete the circuit again.
Another cause can be the electronic module starting to go bad from building up too much charge in capacitors and not relieving or discharging itself to release the high enough voltage to produce the spark. After it shuts down for a while, it discharges itself then will work again until it saturates again then fails again so it wont build up the voltage and drop off after it releases the spark so it can become saturated again repeatedly every time it 'fires'.
Another type of spark tester has a very wide gap to it to show if the voltage is strong enough to jump the large gap that would be simulated when it is under compression. It is also a way of seeing if the coil is getting 'Weak' when it gets hot by using that type of tester. Normally you want to hook it up as soon as your engine dies but it can still show if it is starting to go bad by not being able to jump the large gap built into that tester when the engine is cold and the ignition is working.
 

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Discussion Starter · #4 ·
Thanks for the info. When it shuts down though its as if I turn the switch off. There is no roughness in idle (I'll say) as if it running out of gas. I also thought about a module issues but I cannot find one on my drawings any idea where it might be located if there was one?. As far as I coil opening up I considered that but there are two coils I believe I have two plugs and none of the coils listed for this motor Kohler "CH23S" from what I've found so far are dual output.
Thanks:)
 

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I'm no expert by far but two things I do know:
1) you don't need a carburetor at all for a motor to run! If you take any running motor, remove carb...just an intake hole there and spray something flammable in there it will "run" (quotes because not well, no rpm control, etc)...but it will run.
2) Two coils as you say doubtful they'd fail simultaneously, which is why spark tester at least showing you're getting spark.
You can temporarily remove kill leads from coils. You can't shut it off but that eliminates safety and ignition switch issues.
It's down to two things: no fuel or no spark.
Two things I suggested will at least point you in right direction.

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'81 Gravely tractor, 50's 60's 70's 80's 90's Gravely tractors Various Honda Power equipment
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My Cub GT2523 Kohler Command 23 shuts down after about 15 minutes of mowing. After it sits for awhile (i assume cools downs it starts and goes again for about 10 minutes and shuts down and so on.
I have changed he rectifier, fuel pump/line and filter. I've drilled a hole through the gas cap vent so tank is well vented. I changed the oil and filter 2 days ago and tonight I disconnected the oil pressure safety switch. No improvement. Tonight after it stopping with the oil pressure switch I made it a point to check the fuel filter and it was visibly 3/4 full of fuel.
I'm out of ideas.
Thanks in advance:)
Some of the older model Kohlers had a separate box on the outside of the engine they called 'Smart-Spark' that was a timing module that failed all the time and Kohler replaced the whole ignition system with different coils and wiring harness to do away with it.
There are modules built inside of the coils that do away with breaker points, the electronic ignition module that you would not see.
 

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Does the carburetor have an electric shut off valve? It is a solenoid that will shut down the fuel when you turn off the key. If it looses power, it will seem as if you turned off the key. I have had this problem several times in the past. What made this so difficult to diagnose was it was intermittent. When checking for power to the solenoid it was always good. Check your connections to be sure with the key on, there is power at the solenoid pigtail. I ended up mounting an indicator light on my dash to confirm power at the solenoid. Over time, the connection would get dirty and occasionally loose connection and my dash light would go out or flicker and the engine would die. Just unplugging it and back would fix the problem for a few years.
 

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Discussion Starter · #9 ·
I've been looking to see if there was an electric shut off valve haven't found it yet. But it sounds like from what you mentioned that it may be closer to the carb., really hadn't looked in that area yet. BWT this machine is 2004 vintage.

Thanks for the ideas:)
 

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When you take off the plastic engine cover, you will see a harness & several connectors that go to the coils and then the wire going to the solonoid. I assum you have one since I have a vintage Kohler 22hp. Those connectors are known to get dirty or loose and lose connecton, unplug them, make sure and check they are clean and when plugging in, they grip tightly. Once you find the wire leading to the carb, with the key on, unplug in and out and you'll hear a clicking sound of the solenoid activating. That the the connection I mounted my dash light to.
 
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