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Kohler won't start

Started by Brad_bb, January 24, 2022, 10:18:25 PM

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Brad_bb

2014 LT15go gas Kohler command pro CH620.
I hadn't started the mill in about 4 months.  It's been inside the heated shop the whole time.  I went to start it and after a few cranks it started and ran normall for a few seconds and then started sputtering and I could see liquid fuel at this exhaust pipe connection.


 

So obviously too much fuel, I figured it was flooded.  I didn't have my tools with me so I had to wait for the following week(today).  I pulled the plugs, they didn't look wet wet, but it had been a week.  I cleaned the plugs with a wire brush.  and reinstalled.  Tried starting and nothing.  Pulled plugs again and checked and they looked the same as when I had just cleaned them, not wet fuel on them.  I then reinstalled one and plugged the other one into it's boot and held it against the engine shield and cranked the engine and it was giving good spark.  I reinstalled and tried several more times to start the engine and  it never fired.  I pulled and checked plugs again and nothing on them.  So It seems like I'm not getting fuel.  

I am suspecting one of two things.  Primary suspect is the fuel solenoid.  This is where I need some confirmation.  As I understand, and I have not specific reference for this, the solenoid is the on/off for letting fuel flow into the carburetor.  Kind of like a needle and seat.  Is this correct?  From one youtube video I found, you can get gummy deposits on the solenoid shaft or the seat it goes in.  

The secondary possibility is the fuel pump.  I should have checked this by pulling the hose on the output side and cranking it so see if fuel flows, but I didn't. 

Third possibility is a vacuum leak in the fuel hose between the tank and the pump, Or a clog.  Don't think it's a clog as the fuel filter is new etc.  I doubt a leak as I've had a cracked hose issue before and I reconfigured the fuel hose long ago so as not to have a sharp bend out of the tank.   This possibility can be eliminated by testing the pump and it if flows, then we don't have an air leak in the fuel line.


 

 
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

Ben Cut-wright

How did you determine that wet spot on the hot exhaust was "liquid fuel"?  If the engine only ran a  "few seconds" it might have been condensation.  You stated the spark plugs were dry and did not describe them as being very dark or black as a flooded or rich running condition would color them. 


Spark on one plug is NO guarantee both are firing correctly, but it is a  good indication.  There are better ways to check for NO fuel flow than pulling spark plugs. These require ensuring there is fuel in the tank, shutoff valves are on, hoses and fittings are secure, and simply removing the hose at the carb to check for flow. The fuel solenoid isn't a device to shutoff fuel flow INTO the carb.  It does shutoff flow in a circuit of the carb.  The term shutoff solenoid is a slight misnomer in that the intended purpose is to aid in preventing the carb from continuing fuel flow after the ignition is turned off. It often eliminates destructive exhaust backfires as well.  Occasionally you may read this valve designated as an "anti diesel valve". 


You began with suspecting the fuel shutoff valve and then listed the fuel pump as another possibility.  Begin with, is the pump moving fuel to the carb.  Instead of "vacuum leak", did you mean a leak in the suction side of the fuel line?  Is the choke mechanism operating properly and did you have it completely on/closed?


My comments above are but a few common check points. 



Southside

Well, like you said, first make sure fuel is getting to the carb, after that it could be the solenoid.  On my CH730 it's right on the carb bowl, then it could be the needle valve.  I would pull the carb off and soak it with a good carb cleaner.  I did rebuild the carb on my 730 last year but it was for the opposite reason, getting too much fuel and fowling the plugs.  Lot of small jets on those carbs.    
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Brad_bb

Quote from: Ben Cut-wright on January 24, 2022, 11:09:06 PM
How did you determine that wet spot on the hot exhaust was "liquid fuel"?  If the engine only ran a  "few seconds" it might have been condensation.  You stated the spark plugs were dry and did not describe them as being very dark or black as a flooded or rich running condition would color them.  

I visually saw liquid, and I smelled gas.  I do not believe any condensation, it's in a heated shop and air is dry, no temp swings though dew point.  When I firs pulled plugs, there was some black.  They weren't totally sooted up like an engine that is really running rich, but there was some.  They were not wet with fuel, but a week had passed since the original incident.  So what wetness there may have been could have evaporated in that time.


Spark on one plug is NO guarantee both are firing correctly, but it is a  good indication.  There are better ways to check for NO fuel flow than pulling spark plugs.

I came to that conclusion because I wasn't getting any combustion, I was seeing good spark on the one plug I verified, and in the multiple times I pulled the plugs out, I did not see any liquid fuel.

These require ensuring there is fuel in the tank, shutoff valves (there aren't any fuel shut off valves) are on, hoses and fittings are secure(check), and simply removing the hose at the carb to check for flow(didn't do this one yet). The fuel solenoid isn't a device to shutoff fuel flow INTO the carb.  It does shutoff flow in a circuit of the carb.  The term shutoff solenoid is a slight misnomer in that the intended purpose is to aid in preventing the carb from continuing fuel flow after the ignition is turned off. It often eliminates destructive exhaust backfires as well.  Occasionally you may read this valve designated as an "anti diesel valve".  


You began with suspecting the fuel shutoff valve (no, the fuel solenoid with my limited understanding of what it does) and then listed the fuel pump as another possibility.  Begin with, is the pump moving fuel to the carb(that is what I still need to check).  Instead of "vacuum leak", did you mean a leak in the suction side of the fuel line? YES  Is the choke mechanism operating properly and did you have it completely on/closed? YES


My comments above are but a few common check points.  

The downside is that I had to leave and go back to my new place 3 hours away.  So now I can't mess with it until I go back.  That is why I am asking questions, to try and figure out what I'm going to do when I get back, and get any parts I need before going back.  The fuel pump is not expensive($23) so I think I'll get one to have in case I find that is the problem. The solenoid is $170 on the other hand so I don't think I'll get one yet.  If the pump is not the problem, I can pull the solenoid, if so advised and clean the shaft and make sure it works properly by powering it.





Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

Brad_bb

Quote from: Southside on January 24, 2022, 11:13:13 PM
Well, like you said, first make sure fuel is getting to the carb, after that it could be the solenoid.  On my CH730 it's right on the carb bowl, then it could be the needle valve.  I would pull the carb off and soak it with a good carb cleaner.  Yep, hopefully I won't have to go there....
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

TroyC

Does that engine have an electrical or pulse type fuel pump? If you had raw gas exit the exhaust, check oil level. If the fuel tank is located above the engine, a leaky needle/seat can fill crankcase with raw gas.

Ben Cut-wright

Quote from: Brad_bb on January 24, 2022, 11:56:13 PM
Quote from: Ben Cut-wright on January 24, 2022, 11:09:06 PM

I visually saw liquid, and I smelled gas.  I do not believe any condensation, it's in a heated shop and air is dry, no temp swings though dew point. 

I pulled the plugs out, I did not see any liquid fuel.



You began with suspecting the fuel shutoff valve (no, the fuel solenoid with my limited understanding of what it does)



and then listed the fuel pump as another possibility.  Begin with, is the pump moving fuel to the carb(that is what I still need to check).  Instead of "vacuum leak", did you mean a leak in the suction side of the fuel line? YES  Is the choke mechanism operating properly and did you have it completely on/closed? YES


My comments above are but a few common check points.  

The downside is that I had to leave and go back to my new place 3 hours away.  So now I can't mess with it until I go back.  That is why I am asking questions, to try and figure out what I'm going to do when I get back, and get any parts I need before going back.  The fuel pump is not expensive($23) so I think I'll get one to have in case I find that is the problem. The solenoid is $170 on the other hand so I don't think I'll get one yet.  If the pump is not the problem, I can pull the solenoid, if so advised and clean the shaft and make sure it works properly by powering it.



Exhaust Condensation is not dependent on "dew point", it is a product of internal engine combustion.  Not to get hung up on that, only questioning why raw gas in the exhaust contributed to make you speculate there was NO fuel flow.  Do you know some way liquid gasoline could get into the exhaust in sufficient amount to leak out a pipe joint other than pass through the combustion chambers?

Liquid fuel on spark plugs is flooded.

I was referring to the fuel shutoff "solenoid" valve and felt no need to complete the terminology as I placed the comment in context with your question.  You can shotgun parts or attempt repairs which may or may not complicate a solution. Diagnostic routines will give direction if followed in an orderly fashion.  Carb repair isn't among the first things to consider unless you have some idea of what to expect as the problem.  You haven't even tested the electrical circuit for the solenoid but have knowledge of the price.  Replacing a part because it is easy or inexpensive can create other problems.
 
Good luck.

Brad_bb

Again, I am 3 hours away from the mill.  I need to be prepared for whatever I find.  Having a fuel pump in case that turns out to be the problem is fine to have at $23.  Having a solenoid at $170 is more than I want to do because the solenoid, if that be the problem, could very well just be sticking and a clean up could fix it.   I'm not shotgunning, I'm preparing for contingencies because I won't have as many options once I'm there.

This is why I'm preparing for the likely possibilities as much as I can.  

I'm looking at the flooding and no fuel issue like a stuck needle.  Stuck open, and stuck closed from not being used in 4 months.  I've had the same issue with a tractor in the past.

The point of this post was to try to better understand the fuel solenoid and determine if that could be the no start issue.  I still don't have a clear understanding of it's function.  Does it stop all fuel flow to the carb?

One of the first things to try is check the other plug for spark.
Second is to test if the fuel pump is pumping fuel to the carb by pulling the hose and cranking.  If those check out fine, I was thinking the solenoid would be next?? Again, without a full understanding of how it works, I don't know for sure if it affects starting?

Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

Southside

For under $20 you can get an inline spark tester, basically it connects to your spark plug wire and then to the plug so as the engine is turning or running you visually see the spark in a clear window.  I suspected a bad coil on mine before I determined the carb was actually flooding one cylinder and the inline eliminated that issue without too much effort.  
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Woodmizer LT Super 70 and LT35 sawmill, KD250 kiln, BMS 250 sharpener and setter
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Woodmaster 725 and 4000 planner and moulder
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farmfromkansas

When my Kohler won't start, I try putting a little gas directly into the carburetor, by taking the air cleaner off and pouring the gas in.  Usually hits a few licks.  You may need to put some seafoam in your gas tank to clean up any fuel deposits.
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rusticretreater

I sometimes wake up a sleepy engine by spraying starting fluid on the foam filter and then starting.  Its kinda like coffee for the engine, and gets things going.  If it starts, runs and dies you know that at least the ignition is working.

The service manual for this engine can be found here: https://kohlerpower.com/en/engines/product/command-pro-ch620

I would download the .pdf to a tablet or make sure you can access it on your smart phone.  It shows all the components and has diagnostic procedures plus the tools needed for each test.

Old timey way to check for spark-stick a screwdriver into the spark plug boot and hold it close to some metal while cranking.  You should see the spark.  There are also some quick testers at auto stores.  A small spark plug with spring loaded clamp.  Plug it into the plug wire and clamp it to some metal.  You will see the plug fire when cranking.

They have three different ignition systems for this engine.  While I expect the simplest one to be used, it might be one of the other two.  The manual has diagnostic procedures.  You might need a volt-ohm meter to test the system.  I would expect it to be the simple magnet in the spinning flywheel triggering the coils to fire like most lawnmowers use.  These components get dirty and rust over time.  A tune up would be to clean the pickups and the flywheel and reset the gaps of the pickups.  Take some fine grit sandpaper with you and a spray cleaner.

For fuel, you got the right idea. From the carb, work your way back through each component until you find the piece that doesn't work.

After that it is compression or carb.  Good luck!

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Ben Cut-wright

"The point of this post was to try to better understand the fuel solenoid"


My attempt to contribute a bit of information regarding the device must have been insufficient.


Do not focus on components you do not understand.  Proper diagnosis begins with much more basics than you have done so far.  Do NOT use starting fluids on this engine and MOST other engines.  NEVER use starting fluids unless you have complete understanding of the hazards and risks and follow all proper usage methods.  

TroyC

I believe the fuel shutoff is a solenoid on the carb which closes the fuel passage inside the carb. I have that setup on my Onan welder motor. If it sticks closed (or no electricity to it), engine will not run. As pointed out, a little gas or starting fluid in carb intake will verify electrical system working. I have to 'prime' my welder that way many times as it sits for long periods.

My mill is hours away from home also, understand about traveling with spares. Sometimes my welder fuel pump takes awhile to pump as it is pulse, not electrical. That's why I prime. 


luap

Ben C. gave you the designed purpose of the electric fuel solenoid. You should be able to hear it click when you turn the key to the on position. It could still be gunked up though. I had one come in that a mouse chewed the wire under the shroud and was grounded out. if you do pull the carb bowl off, I suggest you have a new bowl gasket on hand, rather than use the old one. some of the new ones are no longer just a simple o ring style. i also had one where the fuel filter was falling apart and paper fibers were plugging the carb. Might as well add that to your list for what they cost. I don't recommend the small engine style cheap ones. get an inline automotive type. Good luck. The solinoid does not stop fuel flow to the carb, it effectively plugs the main jet in the carb shuttting off fuel to  the bowl and the rest of the carb. so in a way it is a fuel shutoff but not in the sense of what you would commonly think.

randy d

Brad did you shut the shut off valve at the tank the last time you shut down could be easy to forget.  Randy

bannerd

I was working on one of these this weekend, take the plugs off, remove the air filter which should reveal the carb.  Don't choke it and have a look down the barrel.. fuel should be dumping into the combustion chambers.  If you're not getting anything then I suspect the issue is the carb or pump.  You can isolate that by putting the outfeed into a bottle and see if fuel is pumping.  I doubt it's that..   The problem with the 620 I had was inside the bowl was a bunch of gel.  After cleaning all that gunk out I explained to the customer that if he plans on storing this things for longer than a month to just run the engine with the fuel supply off.  It will empty the bowl and the jelly will not form.

I swear half the fuel around here has 10% water.

fluidpowerpro

Change is hard....
Especially when a jar full of it falls off the top shelf and hits your head!

biggkidd

Those electric solenoids purpose is to stop fuel from sloshing in the engine and causing flooding when they are being moved about. They frequently stick when left sitting. Also many of them are a little picky about voltage supply. Often times slightly low voltage will not open them especially if they are sticky. My John Deere mower frequently has this issue with low voltage. 
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jrsloan1

My mill Kohler is a slightly different model but several times I have had won't start issues and it has been fuel related. Seems cedar sawdust is fine enough to get into the carb and cause clogging. I have both an electric and pulse fuel pump. The electric boost to the pulse/ vacuum. Electric went out once and vacuum could not pump adequate fuel to keep it running through the many feet of fuel line. 

On another engine, a briggs and scrap iron on my zero turn mower, the fuel shut off solenoid sticks almost every time it sets for long. When it does, there's not enough batteries in the whole state to get it to run. However, a wiggle on the little round solenoid and it'll start right up. My buddy teases me that I won't replace the solenoid. I told him it's cheap insurance cause can't just anyone steal it!!   

Never use anything but real gasoline in these small engines as long as the guvment lets us 
Never trust nobody cause you can't fix stupid!!!

Ben Cut-wright

Quote from: bannerd on January 25, 2022, 12:52:07 PM
I was working on one of these this weekend, take the plugs off, remove the air filter which should reveal the carb.  Don't choke it and have a look down the barrel.. fuel should be dumping into the combustion chambers.  If you're not getting anything then I suspect the issue is the carb or pump.  You can isolate that by putting the outfeed into a bottle and see if fuel is pumping.  I doubt it's that..   The problem with the 620 I had was inside the bowl was a bunch of gel.  After cleaning all that gunk out I explained to the customer that if he plans on storing this things for longer than a month to just run the engine with the fuel supply off.  It will empty the bowl and the jelly will not form.

I swear half the fuel around here has 10% water.
Just a few comments about personal safety as well as technical techniques.  Replying to your post only because of opportunity and not to be critical of it.

Gasoline vapor is extremely flammable and powerful.  All precaution must be taken when opening lines and fittings. NEVER directly "look down a carb barrel" when an engine is cranking over or running.  A mirror is the correct method but precautions must be maintained even then. There is no reason to check fuel flow in a carb if the fuel isn't flowing to the carb inlet.


Could you explain what you mean by "take the plugs off"?   An engine with no spark plugs does not pump enough air through the carb to create fuel flow.  Without the benefit of choke most small engines will not show liquid fuel at cranking RPM's.


The OP wishes to cover ALL bases because the problem is distant and he has little pertinent knowledge of what might be wrong and what needs to be tested next.  Time will NOT be saved by attempts to rebuild a carb when fuel supply hasn't been determined.  No amount of electrical theory will suffice if spark is *currently satisfactory.  Getting way down into the weeds, without enough compression the impulse fuel pump may not operate.  Normal maintenance items are warranted to have on hand. Getting educated in carb rebuild and repair could complicate the solution needed.   Example: IF the carb is faulty but the repair does not encompass the fault, or creates other faults. Even simple carbs have intricate and complicated functions.

 
Fuel quality can be an issue.  A tiny amount can stop fuel from transferring in a carb.  It is often possible to remove small amounts of liquid water in a carb without complete disassembly.  Adding water dispersals to alcohol/ethanol blends is a waste, IMO. The use  of non-alcohol blends might benefit from using dispersal additives if the amount of water is tiny. But....proper application and techniques must be followed in order to achieve success.  Prevention pays.  

bannerd

Quote from: Ben Cut-wright on January 26, 2022, 10:38:48 AM
Quote from: bannerd on January 25, 2022, 12:52:07 PM
I was working on one of these this weekend, take the plugs off, remove the air filter which should reveal the carb.  Don't choke it and have a look down the barrel.. fuel should be dumping into the combustion chambers.  If you're not getting anything then I suspect the issue is the carb or pump.  You can isolate that by putting the outfeed into a bottle and see if fuel is pumping.  I doubt it's that..   The problem with the 620 I had was inside the bowl was a bunch of gel.  After cleaning all that gunk out I explained to the customer that if he plans on storing this things for longer than a month to just run the engine with the fuel supply off.  It will empty the bowl and the jelly will not form.

I swear half the fuel around here has 10% water.
Just a few comments about personal safety as well as technical techniques.  Replying to your post only because of opportunity and not to be critical of it.

Gasoline vapor is extremely flammable and powerful.  All precaution must be taken when opening lines and fittings. NEVER directly "look down a carb barrel" when an engine is cranking over or running.  A mirror is the correct method but precautions must be maintained even then. There is no reason to check fuel flow in a carb if the fuel isn't flowing to the carb inlet.


Could you explain what you mean by "take the plugs off"?   An engine with no spark plugs does not pump enough air through the carb to create fuel flow.  Without the benefit of choke most small engines will not show liquid fuel at cranking RPM's.


The OP wishes to cover ALL bases because the problem is distant and he has little pertinent knowledge of what might be wrong and what needs to be tested next.  Time will NOT be saved by attempts to rebuild a carb when fuel supply hasn't been determined.  No amount of electrical theory will suffice if spark is *currently satisfactory.  Getting way down into the weeds, without enough compression the impulse fuel pump may not operate.  Normal maintenance items are warranted to have on hand. Getting educated in carb rebuild and repair could complicate the solution needed.   Example: IF the carb is faulty but the repair does not encompass the fault, or creates other faults. Even simple carbs have intricate and complicated functions.


Fuel quality can be an issue.  A tiny amount can stop fuel from transferring in a carb.  It is often possible to remove small amounts of liquid water in a carb without complete disassembly.  Adding water dispersals to alcohol/ethanol blends is a waste, IMO. The use  of non-alcohol blends might benefit from using dispersal additives if the amount of water is tiny. But....proper application and techniques must be followed in order to achieve success.  Prevention pays.  
Seems like you know what you're talking about, I'll step aside then!

Ben Cut-wright

Please do not feel inclined to "step aside", especially IF anything I said contributed to a hesitancy in replying.


Yesterday I was wanting to work a large log splitter.  The Briggs IC carb engine failed to start after running for a few minutes and then dying.  Tested what I could in the woods.  Spark was barely visible but that's not uncommon in certain light and using reading glasses working alone. Spark plug was DRY.  Compression is difficult to determine because of the cold and the engine is direct connected to a good size hydraulic pump.  Rewind starter and I'm a "Dang" old guy.  I use ONLY 91 octane no-ethanol gasoline and keep my fuel tanks FULL unless I'm using the machine. 


Fuel didn't smell bad, was so cold it didn't smell much at all.  So, I elected to do a field test of fuel quality/volatility.  Not something I have done often but lately I find this 'rarely' useful.  Dipped the corner of a paper towel into the top of the fuel tank, maybe an inch got wet.  Carried this to a safe area and tore the paper towel away from the wet area leaving half an inch of dry paper towel.  The dry area REMAINED dry.  Used an open flame to light the paper towel but the DRY portion caught and burned before the wet portion burned. 


Clearly BAD fuel was the problem. Why the fuel in the carb was good enough to start and run contributed to make that a red herring clue.  Drained ALL fuel out of the system including the fuel pump and carb, refilled with fresh fuel, and the engine started in two pulls and ran perfectly. 


Telling this story to illustrate how easily it is to head down a rabbit hole with little or no direct knowledge of tests and results.  Also to highlight your well taken point of "bad gas".  Wasn't water in my gas, wasn't soured gas, it was gasoline that somehow lost its volatility. 

Brad_bb

@randy d , there isn't a shut off valve for the fuel.  Also and FYI, I run only non-ethanol fuel in my mill, saws etc.  It's got almost half a tank, I added a quarter tank of fresh about two months ago to empty my jug so I could go refill it.  If other tests don't pan out, it's easy enough to dump that fuel in my forklift and refill with fresh.

Then again, I have no pertinent information about what the heck I'm doing....  :D ;D :D ;D  

Seriously though, I'll also have to check for a blown head gasket(compression) if fuel is not the problem.  I had to change the head gaskets only 16 mon1ths ago or so.  I had a small blow out on one cylinder.  Some of you may remember my post on that.
It's confirmed, blew a head gasket on the LT15go. in Sawmills and Milling
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

Maine Miller

Better pick up some paper towels on the way to look at it. 8)

TroyC

Quote from: Ben Cut-wright on January 28, 2022, 09:27:06 AMTelling this story to illustrate how easily it is to head down a rabbit hole with little or no direct knowledge of tests and results. Also to highlight your well taken point of "bad gas". Wasn't water in my gas, wasn't soured gas, it was gasoline that somehow lost its volatility.


Mr friend called a couple weeks ago- his pressure washer ran a few minutes then cut out. We went thru the normal check stuff on the phone. Everything sounded good but just wouldn't run. He decided to order replacement carb for about 15.00.

While waiting on the new carb, he disassembled the old carb. Called me back and sheepishly told me he had accidentally gotten his diesel/gas cans mixed. After draining the diesel and cleaning the carb, washer runs fine. At least the engine wasn't damaged. Then he went and bought a real diesel container at Rural King. :D

Happens. I poured a gallon of gas in my diesel tractor once. Caught what I just did and fixed the error.




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