I have a Kohler 25 hp on a lt40 that does not want to sop when I turn the key off. Any idea where I should start my check-up ?
Help! My Kohler 25HP won't shut off! | Tractor Forum - Your Online Tractor Resource and Community (https://www.tractorforum.com/threads/help-my-kohler-25hp-wont-shut-off.22979/)
see if this can help you.
good luck
D
Fuel solenoid
Quote from: curved-wood on May 04, 2020, 02:25:19 PM
I have a Kohler 25 hp on a lt40 that does not want to sop when I turn the key off. Any idea where I should start my check-up ?
How have you been stopping it since the problem?
Does it run poor when you shut the ignition off or does it continue to run well? The isolation diodes can prevent killing one or both coils if open. Don't know if yours had the diodes in the module or the line. Easily tested with a test light.
Does it help if you throttle down to slow idle?
Quote from: Ben Cut-wright on May 04, 2020, 05:16:18 PM
Quote from: curved-wood on May 04, 2020, 02:25:19 PM
I have a Kohler 25 hp on a lt40 that does not want to sop when I turn the key off. Any idea where I should start my check-up ?
How have you been stopping it since the problem?
Does it run poor when you shut the ignition off or does it continue to run well? The isolation diodes can prevent killing one or both coils if open. Don't know if yours had the diodes in the module or the line. Easily tested with a test light.
It does run very poor when I shut off the key. Horrible to ear
Quote from: farmfromkansas on May 04, 2020, 05:46:08 PM
Does it help if you throttle down to slow idle?
No it is not stop if I engage the motor ( which give some throttle ). If I turn the key back on the motor run smooth again. After a few tries it finally stops.
I believe Ben C is pointing you in the right direction. After you shut it off wiggle the wiring harness to see if it shuts off. Sometimes the diodes are connected with crimp on connectors and lose connection.
It could also have hot spots in the cylinders which is igniting fuel without a spark, we always called it "dieseling". Sometimes an old air filter that's falling apart and sucking pieces into the engine can cause this.
The wrong octane rated fuel can too but I wouldn't expect to see that on a small engine. The timing also can't really change on these motors either unless you've sheared the key, and the flywheel has advanced a little, then you'll get some run-on when the key is off.
I've seen oil additives cause this as well, such as marvel.
Otherwise a faulty keyswitch which is allowing power to the coils when off, or other wiring like previously mentioned. I think that's about everything you could possibly check.
Thank you for the suggestions. I dont know why but problems happen only when there is a rush ;D Right now is a total rush for cedar. Anyway... I replace the connector on the coil and it worked for one time but now it return to the same. Could I disassembly the coil to try to clean the connector or those are all sealed?
Quote from: VooDooChikin04 on May 05, 2020, 08:35:14 AMThe timing also can't really change on these motors either unless you've sheared the key, and the flywheel has advanced a little, then you'll get some run-on when the key is off.
The motor seems to clack a little, could it be the timing ? If so is it complex to ajust or I have to send the motor to the specialist ?
Other than shutting down,
How does it start??
You mention it runs fine with the key on
If this is your only problem, don't start chasing maybe's, You have to make sure the keyed circuit is cutting power to the coil(s) consistently first.
Also, check for frayed wires, I recently found a frayed wire going to one of my coils, when I was troubleshooting a charging problem.
Charging problem (https://forestryforum.com/board/index.php?topic=110273.0)
If you can work a test light and a volt meter, I would pull some of the shielding and look at the wiring first.
And while you're in there blow out any sawdust you find especially around the cylinder(s).
D
Quote from: dgdrls on May 06, 2020, 08:21:53 AM
Other than shutting down,
How does it start??
You mention it runs fine with the key on
If this is your only problem, don't start chasing maybe's, You have to make sure the keyed circuit is cutting power to the coil(s) consistently first.
Also, check for frayed wires, I recently found a frayed wire going to one of my coils, when I was troubleshooting a charging problem.
Charging problem (https://forestryforum.com/board/index.php?topic=110273.0)
If you can work a test light and a volt meter, I would pull some of the shielding and look at the wiring first.
And while you're in there blow out any sawdust you find especially around the cylinder(s).
D
So if I understand wright, I should have a signal between the small black wire and the coil when I turn the key off ?
Quote from: curved-wood on May 06, 2020, 12:52:34 AM
Quote from: VooDooChikin04 on May 05, 2020, 08:35:14 AMThe timing also can't really change on these motors either unless you've sheared the key, and the flywheel has advanced a little, then you'll get some run-on when the key is off.
The motor seems to clack a little, could it be the timing ? If so is it complex to ajust or I have to send the motor to the specialist ?
Could it be poor fuel as well? If it is "clacking" when running it could be spark knock or detonation which also causes the "dieseling"on shut off. Try a tank of premium fuel? just an idea.
The flywheel key can shear, timing advances a couple degrees, runs awesome... But runs hot in the cylinders and diesels when shut off. I've watched it happen. So its a possiblity. Timing is non adjustable on Kohler commands as far as I know without getting an aftermarket pickup or flywheel with different key timing.
On a small engine the electric current for the coil is provided by the magnets in the flywheel inducing the current for the coil. The key switch grounds out the coil to shut the engine off. If there is break in that ground wire or if it is disconnected somewhere the engine will not shut off. An engine with an external coil gets its power through the battery/ keyswitch and the keyswitch connects or disconnects the power to the coil. No grounding of the coil takes place.
Quote from: luap on May 06, 2020, 01:05:34 PM
On a small engine the electric current for the coil is provided by the magnets in the flywheel inducing the current for the coil. The key switch grounds out the coil to shut the engine off. If there is break in that ground wire or if it is disconnected somewhere the engine will not shut off. An engine with an external coil gets its power through the battery/ keyswitch and the keyswitch connects or disconnects the power to the coil. No grounding of the coil takes place.
so where should I start testing ?
When I turn off the key the motor is like running on only one cylinder and has a very low rpm.
I've also had those small key switches go bad where they don't stop contact internally. Also recently my tractor which uses a cheap small mower type key switch had corrosion across the terminals on the backside and was arching across. Also need to check that out.
Basically, my gut tells me you have one of two problems based on everything I've read from all the replies here.
1: motor keeps running due to hot cylinder for whatever reason so it diesels on with its own source of ignition.
Or
2: your system is not stopping a coil from receiving power when the key is off, so it keeps on firing and chugging away.
As far as when to start? If it was mine, id start at the key switch. I'd use a multimeter to determine if if it cutting juice when off. Then id move to the coil wiring to see if one is still receiving power when the key is shut off. Next I'd look for chewed or frayed wires where power is able to still reach the coil.
If you don't feel comfortable or do not have the knowledge of using a multimeter, watch some YouTube instructional videos, or find a friend, or ultimately visit a small engine repair place. Sometimes just paying the repair bill saves so much time and frustration.
That said, there is a lot of knowledge here and everyone is willing to help!! :)
A year ago I repowered a compact tractor worn out Onan engine with a Briggs Vanguard. Upon request Briggs provided me a troubleshooting guide and a wiring diagram that showed wire colors and connections. So you should start by reaching out to both WM and Kohler. There are free PDf format manuals on google. That is where I would start my testing. Otherwise if you want to dive into it, start removing panels to expose the back of the keyswitch so you can identify the connections to test them. Each tab on the keyswitch may have a raised letter to identify the connection. B for battery, S for starter, G for ground, etc. It's a process of elimination. My number one rule of troubleshooting is not to replace a part until I have verified it is faulty. Here you are going to get lots of opinions but you need to start with verified information from the manufacture.
Quote from: luap on May 07, 2020, 09:22:02 AM
A year ago I repowered a compact tractor worn out Onan engine with a Briggs Vanguard. Upon request Briggs provided me a troubleshooting guide and a wiring diagram that showed wire colors and connections. So you should start by reaching out to both WM and Kohler. There are free PDf format manuals on google. That is where I would start my testing. Otherwise if you want to dive into it, start removing panels to expose the back of the keyswitch so you can identify the connections to test them. Each tab on the keyswitch may have a raised letter to identify the connection. B for battery, S for starter, G for ground, etc. It's a process of elimination. My number one rule of troubleshooting is not to replace a part until I have verified it is faulty. Here you are going to get lots of opinions but you need to start with verified information from the manufacture.
Recognizing nomenclature and having diagrams in hand will not ensure competent testing or result in comprehensive interpretation of the results. One must be able to apply what diagrams and schematics depict to the actual working of the components. Failing this ability, opinions on what to test and the results of experience can be helpful.
"A process of elimination" can also dictate replacing a component that is otherwise impossible to find faulty.
The OP asked for assistance while providing only a description of the behavior. There are a limited number of causes for the fault he described. Replacing parts wasn't promoted. Testing using simple tools should resolve his problem.
The description the OP gave indicates he isn't chasing a fuel problem. Therefore, some ignition source is the reason the engine will not shut off. Experience would quickly determine whether the engine was dieseling or that only one cylinder was running properly. If dieseling is suspected, quickly opening the throttle to wide open will kill the engine.
The OP states his engine does not stop when he engages the blade but does eventually stop when he cycles the key switch.Testing for ignition spark can be done by several methods. If spark is not extinguished at key-off, testing the few points of interest is simple and requires only basic test tools.
Here is where I would start, google this for the kohler manual: /www.kohler-engine-parts.opeengines.com/index.php?main_page=document_general_info&products_id=34596
Go down to, Kohler Command Pro Horizontal Twin Service Manual and open it up. Print off pages 35/36. ( wiring diagram/ connector identification table)
If grounding is good the engine should stop when the key is turned off.
1) Check the key switch for continuity to ground.
2) Remove the front cover and check the ignition kill circuit, Item D to U to AK of the key switch for continuity.
One additional thought, if the fuel shut off solenoid is not closing it may try to run from the internal cylinder heat, so with the key off check for power at location X. Their should be no power with key off.
Hope this helps or post back with your results.
Mine did it to and it was the fuel shut of it is on the control side of the motor I bought a new valve I was able to replace it by trimming abou a 1/4 in of the shroud you might be able to clean the old one
This tool would help you determine if it is shutoff problem or the dieseling problem.
Amazon.com: Oregon 42-031 Spark Tester, Black: Garden & Outdoor (https://www.amazon.com/Oregon-42-031-Small-Engine-Tester/dp/B0000AXCOV/ref=sr_1_3?dchild=1&keywords=inline+spark+tester&qid=1588888162&sr=8-3). or google inline spark tester
Curved-wood,
does the motor have a carburetor or, is it fuel injected??
D
Quote from: Ben Cut-wright on May 07, 2020, 12:39:40 PMIf dieseling is suspected, quickly opening the throttle to wide open will kill the engine.
I am still doing some test. Opening the throttle with key at off didn't change anything.
I have tested the current between the starter and the coil, and in an out of the coil and everything is OK. The engine run correctly on full power. The valves are noisy a bit but not too bad
Is there a way to test if the problem is the ignition switch ?
Yes. With key in the on position, find which terminals are being connected to power. I typically will find the power terminal which is provided battery power, then turn my meter to a continuity test position. Next hold a test lead on the power terminal and verify which pins are receiving a connection by touching the other test lead on the rest of them. Then turn the key off and check those same pins. None should signal anything. Its a first crude step to finding a blatant connection in the switch. Also make sure the back of the key switch is clean and free of corrosion. A video of the issue would help as well.
FWIW I had a twin cylinder briggs on a riding mower that did the same thing. All I had to do was idle it down and let it run for a minute to cool it down, Then shut it off and it would stop as it is supposed to.
" Is there a way to test if the problem is the ignition switch ?"
Yes, do a continuity test between the power terminal and the terminals on the switch for each position.
I have the same mill it has a fuel shut of valve that when you turn the key off it shuts the fuel of to kill the motor, there is nothing to kill the spark only the fuel shut off mine got sticky and would not close, I bought a new valve and it salved the problem , I cleaned the old one and saved it because I believe it will work now,
Quote from: Gary Davis on May 09, 2020, 10:40:20 AM
I have the same mill it has a fuel shut of valve that when you turn the key off it shuts the fuel of to kill the motor, there is nothing to kill the spark only the fuel shut off mine got sticky and would not close, I bought a new valve and it salved the problem , I cleaned the old one and saved it because I believe it will work now,
Quote from: luap on May 06, 2020, 01:05:34 PM
On a small engine the electric current for the coil is provided by the magnets in the flywheel inducing the current for the coil. The key switch grounds out the coil to shut the engine off. If there is break in that ground wire or if it is disconnected somewhere the engine will not shut off. An engine with an external coil gets its power through the battery/ keyswitch and the keyswitch connects or disconnects the power to the coil. No grounding of the coil takes place.
Boy am I confused. What engine are we working with ? The old K series, had an external coil and no kill wire, but it did not have the electric fuel shut off . The CH engine has the electric fuel shut off and a kill wire. The kill wire is a safety feature for when the electric fuel shut off fails, along with the low oil pressure switch which grounds the system in the event of low or loss of oil pressure. Please correct me if I am wrong..
Modification :" Please correct me if I am wrong.." well I am wrong and nobody corrected me. In this statement, " The kill wire is a safety feature for when the electric fuel shut off fails". What I meant to say was the kill wire is the main shut off for normal operation and all so for when the electric fuel shut off fails, along with the low oil pressure switch which grounds the system in the event of low or loss of oil pressure.
Quote from: Remle on May 10, 2020, 11:03:44 AM
Quote from: Gary Davis on May 09, 2020, 10:40:20 AM
I have the same mill it has a fuel shut of valve that when you turn the key off it shuts the fuel of to kill the motor, there is nothing to kill the spark only the fuel shut off mine got sticky and would not close, I bought a new valve and it salved the problem , I cleaned the old one and saved it because I believe it will work now,
Quote from: luap on May 06, 2020, 01:05:34 PM
On a small engine the electric current for the coil is provided by the magnets in the flywheel inducing the current for the coil. The key switch grounds out the coil to shut the engine off. If there is break in that ground wire or if it is disconnected somewhere the engine will not shut off. An engine with an external coil gets its power through the battery/ keyswitch and the keyswitch connects or disconnects the power to the coil. No grounding of the coil takes place.
Boy am I confused. What engine are we working with ? The old K series, had an external coil and no kill wire, but it did not have the electric fuel shut off . The CH engine has the electric fuel shut off and a kill wire. The kill wire is a safety feature for when the electric fuel shut off fails, along with the low oil pressure switch which grounds the system in the event of low or loss of oil pressure. Please correct me if I am wrong..
The above is a great example of why it is so difficult to accurately diagnose with scant information to begin with. The vast changes and different components and methods of operation make it impossible to do much more than ask further questions and offer ideas.
Spark ignition can be attained by several methods. Whether the ignition is battery operated or magneto powered normally dictates how the source voltage is extinguished. So far, there has only been speculation as to the exact ignition system in this thread. Such a simple item is so very important to sensible advise. We can't even be certain there is a fault in the normal ignition system yet.
Nevertheless, spark ignition is either shut down by cutting power or grounding the magneto circuit. This engine must kill both mags to kill the engine. To prevent feedback and utilize a single kill wire, diodes are incorporated in the circuit. To someone who had NO knowledge of spark ignition the differences in operation may seem less than obvious.
Fuel-cut alone is a very poor method of killing an ICE engine. In some circumstances it will fail completely to achieve its goal. Many of the fuel-cut devices are meant to prevent engine back-fire, and fail miserably in that aspect in some applications.
The OP must determine what method his engine uses to generate spark energy, battery or mag. Easy enough to do that instructions should not be needed. After that it is only a matter of what failed. Again easily determined by test light or meter, IF you know what you are testing for and what the test results mean.
OP states: The engine runs normally key on and under load. The engine runs ragged at key off but fails to immediately die. The engine continues to run key-off even when the throttle is opened or if the engine is slightly loaded. NO fuel fault will cause this engine to continue running for a length of time under the set conditions given. This engine is seeing an ignition source. Someone with experience would immediately recognize a dieseling gas engine.
Correction on one point. Low oil shutdowns may be direct grounding, or they may interrupt low voltage.
I did not ask What the model # of the engine in question is which if known will answer a lot of the questions . Looking at Jack's small engines parts lookup they list 18 model numbers for a 25 hp Kohler.
I assumed.... lol... it was most likely a ch25.. or kohler command 25hp. The only older kohlers ive seen we 20hp or much larger, have never come across an OLD 25hp. But the basic methods I detailed out should cover most engines with a simple key ignition switch.
Really a video of the situation would immediately help. IF its dieseling it will be VERY rough, bucking, shaking, snorting and barely going. IF its a faulty diode allowing power to backfeed it would just be running on the one cylinder which would be rough but would run and probably would rev up with the increase in throttle. IF its a short in the key switch, you could get intermittent or weak firing on both cylinders which could cause rough running.
Agreed, we need more information.
Okay gentlemen, how about this theory. Perhaps one ignition module is being grounded and the other is not. This would the extended run on one cylinder until fuel from the carb ran out.
Take ignition switch out and clean terminals with contact spray and test it with continuity (beeper) or just buy a new ignition switch.
Still testing. yesterday I try to shut it down immediately after starting when the engine is still cold. It shut out normally . Try that after lunch when engine is still cold and still shuts down nicely. Am I correct to assume that it is not the switch ? Right now the only way that I could shut the engine is by disconnecting the fuel line till there is no gaz to burn.
Quote from: Remle on May 11, 2020, 12:56:34 AM
Okay gentlemen, how about this theory. Perhaps one ignition module is being grounded and the other is not. This would the extended run on one cylinder until fuel from the carb ran out.
If I go with the sound that could be an explanation. When I put the key on off the motor as a sound similar to running on one cylinder. But if that's the problem would it affect the performance when I am sawing ?
Quote from: curved-wood on May 11, 2020, 06:24:34 AM
Quote from: Remle on May 11, 2020, 12:56:34 AM
Okay gentlemen, how about this theory. Perhaps one ignition module is being grounded and the other is not. This would the extended run on one cylinder until fuel from the carb ran out.
If I go with the sound that could be an explanation. When I put the key on off the motor as a sound similar to running on one cylinder. But if that's the problem would it affect the performance when I am sawing ?
What sound? The engine sound will be distinctly different to the experienced ear if one cylinder is dead compared to the sound of dieseling. Have you come to the conclusion or have testing which decidedly points to one or the other?
How about some feedback on what ignition system you have, what exact engine, what test results you have acquired? This is NOT a difficult problem to test and repair.
Quote from: curved-wood on May 11, 2020, 06:18:14 AM
Still testing. yesterday I try to shut it down immediately after starting when the engine is still cold. It shut out normally . Try that after lunch when engine is still cold and still shuts down nicely. Am I correct to assume that it is not the switch ? Right now the only way that I could shut the engine is by disconnecting the fuel line till there is no gaz to burn.
The scenario you describe above is not testing, it is an anecdotal description of events. NO assumptions should be adopted in this case since testing to confirm is simple and quick, requiring no expensive test tools or difficult analysis. Understanding how to test the ignition switch, doing the tests, and confirming the switch as sound or faulty takes less time and skill than posting to a thread on the internet. Eliminating the switch, as well as testing the entire electrical control circuit for spark ignition on this engine, can be accomplished using a....test light.
It is hard to imagine how this engine could diesel long enough to empty the fuel lines and the carb. This small engine might stumble and cripple along while dieseling, but it will NOT make enough power to continue running under load. Not saying it isn't dieseling, only saying your description of the fault and the information provided are contradictory at best.
Good luck.
My motor model is ch730s
Here is the tests that I've done:
- Stop easy when the motor is cold
-I've got continuity through the solenoid
-11.94 at the battery and at the switch
-key off : at the switch 11.9 between the ground (small black wire in the middle ) and the power (big red wire from the battery ) . at the solenoid : 11.9 between the ground ( small black wire ) and the power source
- key on: at the switch .06 between the ground and the power (big red from the battery. At the solenoid : .25
Is those numbers are helpfull?
Quote from: curved-wood on May 11, 2020, 02:37:03 PM
My motor model is ch730s
Here is the tests that I've done:
- Stop easy when the motor is cold
-I've got continuity through the solenoid
-11.94 at the battery and at the switch
-key off : at the switch 11.9 between the ground (small black wire in the middle ) and the power (big red wire from the battery ) . at the solenoid : 11.9 between the ground ( small black wire ) and the power source
- key on: at the switch .06 between the ground and the power (big red from the battery. At the solenoid : .25
Is those numbers are helpfull?
Model number indicates engine family and size. Need the specification number for exact engine details. There are at three distinct ignition systems for this engine family, two are related, one completely different. Sorry I didn't explain further how to get full engine ID.
The additional info above does not help. Let me try to explain why I say that. Do not feel obliged to answer my questions in the numbered replies below.
1. "continuity" is not a test result. How much continuity, to what solenoid (probably the carb), what should the reading actually be, how did you measure?
2. "11.94" is a precise measurement of voltage. It is low but probably sufficient. It means you have a battery in the circuit.
3. Kohler ignition switch wiring and WoodMizer switch wiring schemes differ. The terminals you tested won't reveal much unless the particular wiring diagram for your mill is understood. The numbers you provided do not specify value?
(Modified the comment below to better apply to this particular engine.)
Does your engine have DSAI (digital spark advance ignition) ignition coils ? If the engine has a DSAI ignition, it is battery powered. These normally
interrupt battery voltage to the primary side of the coil to kill the engine.
Magneto ignition is powered by primary electrical energy from the rotating magnets on the flywheel. These normally using a
grounding circuit to kill primary voltage at the coil.
IMO, if actual tests are properly conducted on the ignition system, testing for proper operation dependent on what type ignition system is being tested, it is quick and easy to determine a fault or determine the system is working as designed and the fault lies elsewhere. Battery supplied low voltage ignition systems require voltage at the coil primary to power the coil, interrupt this voltage and the coil no longer provides spark. Magneto ignition systems require a sound ground circuit to kill the engine. Both types and all three variants provide spark at the plug gap. But the two types make primary voltage for the coils by different means and have completely opposite methods to shut the coils down.
My advice would be to focus on eliminating the most likely fault before trying to juggle several possibilities at the same time. When you prove the ignition is working properly, then move on to other probabilities. Testing terminals without much idea of what to expect or little understanding of what each terminal is doing can be fruitless. Example: Battery ignition can be tested at the positive terminal of the coil to determine if the circuit is working properly to that point. A grounded test light with probe touching the positive side of the coil will illuminate when key is on, and extinguish when key is off. Done deal if it behaves in that manner. Further testing will be required if it does not, but at least your will be on the correct trail.
Again, let me apologize if it appears anything I write complicates my explanation.
easy solution call woodmizer and ask them I have found that they have always been very helpful when I call , as I said I have the lt40 with a 25 horse kohler command when I had the same problem they to to check the vaulve its right behind the choke lever , mine was so bad it would not close at all ,but it could be posable that it could work intermittently do to cold, ethanol fuel , dirt ,etc or any thing that would make the vaulve stick , mine was dirty and cleaned up and works fine, 8)
All the CH engines have a " kill switch (or key switch) which grounds modules to stop engine" be it Fixed Timing, Variable ignition timing or DSAI ignition.
The two ground wires from the ignition modules join together on one wire to the key switch, I'm thinking one of those wires is the problem. Here is a way to check if the ground is bad on one of the ignition modules, hook a spark tester or old neon timing light to a plug wire. Start the engine, observe the tester, it should flash each time the plug fires, turn off key, test light should go out instantly, that means the kill wire to that ignition module is good/ grounding out the module. If the test light continues to flash after the key is turned off, that indicates the kill wire is broken and not grounding the module as it should. Check both plug wires, I think one will test good ground and the other not. Even thought the fuel supply solenoid shuts off with the key, the ignition module with NO ground continues to run off the fuel left in the carb or leakage bypassing the solenoid, even so a properly grounded ignition module should stop the engine. If one of the grounds tests bad pull off the front cover and check the ground wire associated module. It may be a corroded connection or a mouse may have chewed the wire/ ect.
Quote from: Remle on May 11, 2020, 09:37:43 PM
All the CH engines have a " kill switch (or key switch) which grounds modules to stop engine" be it Fixed Timing, Variable ignition timing or DSAI ignition.
The two ground wires from the ignition modules join together on one wire to the key switch, I'm thinking one of those wires is the problem. Here is a way to check if the ground is bad on one of the ignition modules, hook a spark tester or old neon timing light to a plug wire. Start the engine, observe the tester, it should flash each time the plug fires, turn off key, test light should go out instantly, that means the kill wire to that ignition module is good/ grounding out the module. If the test light continues to flash after the key is turned off, that indicates the kill wire is broken and not grounding the module as it should. Check both plug wires, I think one will test good ground and the other not. Even thought the fuel supply solenoid shuts off with the key, the ignition module with NO ground continues to run off the fuel left in the carb or leakage bypassing the solenoid, even so a properly grounded ignition module should stop the engine. If one of the grounds tests bad pull off the front cover and check the ground wire associated module. It may be a corroded connection or a mouse may have chewed the wire/ ect.
You are correct that the switch grounds the spark advance modules to kill the engine. DSAI does require battery voltage to operate, unlike smart spark and fixed timing mag ignitions. DSAI includes a dedicated ground circuit that isn't switched. I should have included both power and ground explanations but I feared I already added too much info without knowing the particular type in question. Thank you for catching that as I had modified that original reply in haste.
For ID purposes.
Fixed timing ignition modules have a single primary wiring terminal, ground.
Smart-spark has two primary terminals, ground and advance.
DSAI has three primary terminals, battery positive, switched ground, and dedicated ground.
Wowy thanks for all the info .i am having an advance mechanical course. I hope that all that info serve other members.
Motor family :6khxs72526c
Model :ch730s
spec:ch730-0039
date :5/10/2006
Today I am going to do some testing that members had suggested ...even mices traces
When you shut it off and it continues to run, pull the plug wires and see if it stops. If it stops you have electricity finding its way to the coil and need to look into your switch/coils, if it doesn't then you have a dieseling situation and need to look into your fuel supply or timing. That is the simplest way, although crude to determine what is causing your situation.
Levi
All this talk about grounding reminded me about our lawnmower when I was a young teenager, it was a old Gravely tractor that the motor gave up on so dad removed the original motor and added a new horizontal crank B&S on it. The kill switch was a metal tab that flipped over to the top of the spark plug to ground the un shielded plug wire end.
So I went to put the mower away and as usual in one motion slid my hand off the wood handle on to the metal part to pull my self forward on the seat as I swung my foot up to flip the kill over to the plug and dismount the seat and walk away as the mower came to a stop. But.... I missed the switch and got the plug stuck in a hole on the top of my sneaker and proceeded to shutoff the mower engine by grounding it out with my toe, up my leg and down my right arm to the handle which seemed to take forever as my right arm tensed up with every spark as the engine slowed down an finely stopped. electricuted-smiley
All that to say try not to zap yourself if pulling plug wires.
Quote from: reride82 on May 12, 2020, 03:19:54 PM
When you shut it off and it continues to run, pull the plug wires and see if it stops. If it stops you have electricity finding its way to the coil and need to look into your switch/coils, if it doesn't then you have a dieseling situation and need to look into your fuel supply or timing. That is the simplest way, although crude to determine what is causing your situation.
Levi
I got it ! I've pull the plugs wires an the engine stops. It is on one side only. So I will check the grounds. Why it does always happen in a sawing rush? ...so many order to fill in cedar. Thanks for the info
I stopped at woodmizer today to get some belts and asked about your problem their tech said the only shut off is the fuel shut off this is why when you turn it off the motor speeds up for a second until all the fuel is burnt then it shuts off he said most of the time all you need to do is to clean the vaulve if you want a new one I got mine at https://www.kohler part number2475701 this info is for the kohlar command 25 horse
Quote from: Gary Davis on May 13, 2020, 09:49:12 PM
I stopped at woodmizer today to get some belts and asked about your problem their tech said the only shut off is the fuel shut off this is why when you turn it off the motor speeds up for a second until all the fuel is burnt then it shuts off he said most of the time all you need to do is to clean the vaulve if you want a new one I got mine at https://www.kohler part number2475701 this info is for the kohlar command 25 horse
Hello Gary,
My comments to you are meant to discuss the difficulty of technical assistance via the written word. Perhaps we can agree about a few particulars in this thread, "kohler won't stop".
The WoodMizer tech you spoke to informed you that "the only shut-off is fuel shut-off". Certainly do not have any critique of your input, you obviously are trying to assist the OP. It is quite obvious the tech's information is NOT correct. According to the OP, this engine continues to run with the key off, additionally it continues to run with only one spark plug wire disconnected. The OP states, "It is on one side only"
The OP does not provide info to support the "one side only". Key on, engine running he would have the same results when disconnecting the spark plug wires. Key off, engine running, he would certainly have different results, but those results would have to be interpreted. IOW, some basic knowledge would have to be applied to the test results in order to give direction.
Several replies commented on a fuel solenoid. How could we equate the fault, as it was explained, to a malfunction in the fuel solenoid? How could the fuel solenoid contribute to the engine running on a single cylinder? The WoodMizer tech didn't have all the pertinent information, and we didn't either. Even so the very first reply in this thread linked to useful pertinent info and here we are, the rabbit has made his circle. Maybe.
The scent is strong on the trail right now. This rabbit can be shot, skinned, fried and eaten if..... the dogs stay with the hot scent. There are still a few holes a cagey rabbit could hide in, but they are limited now. Listen, is that Ol' Rattler out in front?
If he has the kohler command 25 like mine the only shut of is the fuel solenoid turn the key off the valve shuts the fuel of and the engine dies, if the vaulve only closes part way and not completely, and,, as long as the engine gets gas it will run on one cylender remember I have the same mill and engine and had the same problem, being it is the easiest part to check that is where I would start. the woodmizer techs that I have talked to always gave me good information, If you believe woodmizer is wrong go argue with them if you want to keep chasing rabbits go ahead I am done
The motor on my 1997 WM Lt30 is shut off by the fuel solenoid only.
Right now I am slow to do the proper testing du to an overload on the cedar demand. Right now I am just unpluging the spark plugs to shut down the engine. I still have my old motor so change the solenoid fuel is with no cost beside the time to do it which I dont have right now. At least business is strong
Thanks for all the comments, I am learning a lot
Hind sight it seems so obvious, engine shuts down with fuel solenoid. Engine not shutting down with key off.. fuel solenoid must be allowing fuel through.
It ain't just kohler. My mill has a 25 hp kawasaki and there is a fuel shutoff solenoid in the carb. Larger briggs engine on neighbors norwood also has one.
Based on the OP having a CH 730S engine,
http://www.kohlerengines.com/engines/onlinecatalog/pdf/sm_24_690_06.pdf
Per the service manual for CH18-CH25, CH620-CH730, CH740, CH750 edited (the S designation means electric starter, not pertinent to)
Fixed Ignition System
● 1 kill switch (or key switch) which grounds modules to stop engine.
Smart-Spark TM Advance Ignition System
Digital Spark Advance Ignition (DSAI) System
● 1 kill switch (or key switch) which grounds spark advance module to stop engine.
Could the fuel solenoid/anti after-fire valve be bad, sure it could, but its not there to starve the engine to stop it
grounding the ignition stops it.
D
For any one whom believes that the fuel solenoid stops the engine, tell me why only one cylinder continues to fire multiple times in a row and the other cylinder doesn't fire, both draw fuel from the same place.
WoodMizer utilizes wiring schemes on their sawmills that often have to be made compatible with the particular engine option used. NO matter, there are only so many ways to turn this engine OFF. There are schemes where the ignition switch provides battery voltage to the ignition, and schemes whereby the ignition switch grounds the magneto circuit. Reviewing many wiring diagrams for LT30 and lT40 mills in the OP's year range did not reveal other *standalone methods.
The specs the OP provided, the descriptions he gave of the fault, and the results he attained by removing the spark plug wires one at a time, give much credence to the hypothesis that secondary ignition continues to provide spark....on one cylinder....at key off.
Fuel cut solenoids are easy to replace, but they are pricey components to throw at a repair without a sound diagnosis.
Quote from: Remle on May 15, 2020, 12:50:41 PM
For any one whom believes that the fuel solenoid stops the engine, tell me why only one cylinder continues to fire multiple times in a row and the other cylinder doesn't fire, both draw fuel from the same place.
Well gents it's a day later. Yesterday when I posted their were 1945 views, today their are 1976 views with no one offering up an answer to the question. So here is the answer, IMHO, the one cylinder is shut down by the kill circuit and the kill circuit is compromised or ignition module to the one firing is defective. Some have offered up that the OP should just pull the plug wire to stop the engine, as a temporary soultion. It seem he agrees with this, how ever, IMHO, it introduces a new set of problems. Their are 4 that I can think of off the top of my head, 1) each cycle fuel is being drawn in to the non firing cylinder, wetting the plug/washing down the cylinder walls. 2) it empties the carb. 3) it's putting way more stress on the rod in the firing cylinder, it's now carrying the load from the non firing cylinder by pushing it through the intake, compression and exhaust strokes as well as it's own. 4) restarting the engine with a wet plug/washed cylinder and refilling the carb means more revolutions necessary to start the engine are required putting additional strain on the starter. Now I cannot eliminate all of these problems, but the 2 most detrimental # 1 and 3 can be avoided. If he, instead of shutting off the key switch and pulling the plug wire, were to leave the key on, so both cylinder continue to fire and pull the feed to the carb relay, it will eventually drain the carb and stop in a more controlled way. IMHO the " clacking " he reported would stop. The controlled way, IMHO, is why the manufacture added the carb relay, tied it to the oil pressure sensor, as an emergency way to shut down the engine in case of lost oil pressure and not the normal system to stop the engine, that is the function of the heavily debated kill wire.
Now one more thing to rember, turn off the key after the engine stops to prevent the movement of the rest of the functions activated by the key and of coarse plug the carb solenoid wire back in before trying to restart the engine.
Again these are just my opinions, so take them or leave them as you see fit.
Using the link provided by dgdrls and looking in the manual, it identifies a white wire from each ignition module as the kill wire. These two wires are connected to a single white wire that goes to the key switch. A black wire goes from the key switch to ground. Possible broken white wire or connection on the module for the cylinder that keeps firing or a problem where connection is made with single wire to keyswitch. This has been a long thread with good information and a stopgap solution is no fix. Having worked my career in maintenance this would irritate me no end and would be fixed right regardless of what the production manager demanded.
Not sure if the kohler engine is the same but we have a Farris riding mower that has a kohler motor.
After I over hauled the motor you could not stop it from running. Talked to a farris dealer and he said
coils have a single wire that grounds them to kill the motor. We bought some off ebay and that fixed
the trouble but it didn't run to good. So we bought coils from the farris dealer, real kohler coils and now
it runs good and stops when we turn it off. PS just buy real kohler parts.
Sawwood
Quote from: sawwood on May 16, 2020, 08:47:04 PM
Not sure if the kohler engine is the same but we have a Farris riding mower that has a kohler motor.
After I over hauled the motor you could not stop it from running. Talked to a farris dealer and he said
coils have a single wire that grounds them to kill the motor. We bought some off ebay and that fixed
the trouble but it didn't run to good. So we bought coils from the farris dealer, real kohler coils and now
it runs good and stops when we turn it off. PS just buy real kohler parts.
Sawwood
Thanks for relating your similar experience. Do you recall
why this problem appeared after the engine was overhauled? What changed or what component-s failed that were operating properly before the engine repairs? Did both coils continue to provide spark or, like the OP's engine, run on one cylinder?
OEM parts are often the best choice. Do you recall how "didn't run too good with ebay parts" was diagnosed as faulty coils?
Why made the overhaul necessary?
Pardon all the questions, thanks for any answers you may provide.
Not sure why the trouble started after overhauled. Yes both coils provided spark and the
ebay coils would some times make the engine backfire. We had to overhaul the engine
because one cylinder the piston rings had broken and there was a loss of comp. After we
installed the factory coils it ran better and no back fire. The old coils the kill circuit was what
was bad and it would not stop when the key was turned off. Hope this helps.
Sawwood