# Gravely 20G - no spark



## Hathubha (Sep 24, 2013)

I recently purchased a Gravely 20G with around 430 hrs on it. It had sat for a year and the PTO clutch was stuck. After fixing the clutch and cleaning the carb, I noticed that it kep running out of fuel in the fuel filter after it warmed up. I ended up replacing fuel pump and plugs. Now, I have a new problem. I am not getting any spark even tho the flywheel turns freely. I bought a new coil and tried it but it did not fix the problem. I tried unhooking the ground from the coil, but still no spark. The motor is a Kohler M20-s. Any assistance or guidance will be much appreciated. Grass is now catching up with me...

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## sixbales (May 18, 2011)

Howdy Hathubha,

I presume that you have a magneto-type coil mounted adjacent to the flywheel?? Clean the magnet faces and any other dirt on the flywheel. Use a business card for gapping between the armature poles and magnets.

It is difficult to see spark in daylight.....try it in a shaded area or in darkness. Check for spark using a spark plug held against a good metal ground. Could also be a bad plug?? Even a new plug can be bad...It happens


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## Hathubha (Sep 24, 2013)

sixbales said:


> Howdy Hathubha,
> 
> I presume that you have a magneto-type coil mounted adjacent to the flywheel?? Clean the magnet faces and any other dirt on the flywheel. Use a business card for gapping between the armature poles and magnets.
> 
> It is difficult to see spark in daylight.....try it in a shaded area or in darkness. Check for spark using a spark plug held against a good metal ground. Could also be a bad plug?? Even a new plug can be bad...It happens


Hi, thanks. Yes it is an ignition coil mounted to the side of the fly wheel. I did clean up all the rust on the flywheel and tried with a brand new coil as well. The plugs are also new. But somehow I just cant seem to get a spark. Tried testing the plug wire off also. When it first happened after I replaced the fuel pump, it started randomly one time and idled properly, but when I put the cover back on, it stopped. Since then I cannot get it to start again. Have tried everything I can think of.

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## FredM (Nov 18, 2015)

When you say "put the cover back on" is this the blower housing ?, if it is, then I would check the H.T. plug wire from the coil and check and see that you haven't caused a short by pinching the lead when the cover was replaced, this is easy enough done on some engines.


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## Hathubha (Sep 24, 2013)

FredM said:


> When you say "put the cover back on" is this the blower housing ?, if it is, then I would check the H.T. plug wire from the coil and check and see that you haven't caused a short by pinching the lead when the cover was replaced, this is easy enough done on some engines.


Yes, it is the blower housing. Has a rectifier mounted on top of it, that has a 3 prong set up. I ll check the wires again. The Kohler M20-s has 2 plugs and 2 wires from the coil as well as a ground. Neither of the plug wires are firing at the moment.

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## FredM (Nov 18, 2015)

my suggestion of a short in a plug lead is a long shot, I brought up your engine and the coil is a crossfire coil and if you short either lead, this will possibly kill the spark output.

If you have a multimeter, set to ohms and check the earthing circuit between the soft iron core of the coil to the engine housing, if there is no circuit to earth, this will also negate any spark, while you are doing this, have a look at the flywheel key and keyway checking to see that the key hasn't sheared.

if you can get hold of a clear plastic shirt box lid from the old days, this makes a good coil air gap tool, you may be able to find something similar, cut this long enough and wide enough so both poles of the ignition coil are covered, when doing the air gap rotate the flywheel magnet away from the coil and then move the coil away from the flywheel a bit, place the air gap tool between the coil and flywheel and rotate the flywheel magnet so both coil poles are equal on the magnet and then loosen the coil holding screws and allow the coil to pull against the magnet and then tighten the coil holding screws, if the coil air gap is to wide, this will prevent spark also.


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## Hathubha (Sep 24, 2013)

FredM said:


> my suggestion of a short in a plug lead is a long shot, I brought up your engine and the coil is a crossfire coil and if you short either lead, this will possibly kill the spark output.
> 
> If you have a multimeter, set to ohms and check the earthing circuit between the soft iron core of the coil to the engine housing, if there is no circuit to earth, this will also negate any spark, while you are doing this, have a look at the flywheel key and keyway checking to see that the key hasn't sheared.
> 
> if you can get hold of a clear plastic shirt box lid from the old days, this makes a good coil air gap tool, you may be able to find something similar, cut this long enough and wide enough so both poles of the ignition coil are covered, when doing the air gap rotate the flywheel magnet away from the coil and then move the coil away from the flywheel a bit, place the air gap tool between the coil and flywheel and rotate the flywheel magnet so both coil poles are equal on the magnet and then loosen the coil holding screws and allow the coil to pull against the magnet and then tighten the coil holding screws, if the coil air gap is to wide, this will prevent spark also.


I ve re tested the coil gap, checked all wiring. Still no luck. Cld it be the oil sensor gone bad? I even changed out the ignition switch. Bummed at this point. What wld cause the coil to not spark????

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## FredM (Nov 18, 2015)

have you tried for spark with the kill wire removed from the ignition module?, that is the single wire that connects to the spade connector on the coil body, you will have to have one spark plug screwed into the cylinder head as part of the circuit and the other grounded good when spinning the engine.

have you done a resistance test on the coil HT leads to soft iron body ?, I think 30K ohms is the accepted figure, but can go as high as 42K ohms and in the mid 20K ohms.

The new coil you have purchased, would this be genuine or a Chinese import ?, sometimes these will work, but most times don't.

have you tried the original ignition module again ?, try that and leave the kill wire off of the coil spade, if you get spark, then you will have to chase down the problem in the wiring/safety sensors.

is the flywheel magnet strong enough to hold a large screw driver ?, it is possible that the magnet has lost magnetic attraction, I have heard of this but never came across this problem.


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## Hathubha (Sep 24, 2013)

FredM said:


> have you tried for spark with the kill wire removed from the ignition module?, that is the single wire that connects to the spade connector on the coil body, you will have to have one spark plug screwed into the cylinder head as part of the circuit and the other grounded good when spinning the engine.
> 
> have you done a resistance test on the coil HT leads to soft iron body ?, I think 30K ohms is the accepted figure, but can go as high as 42K ohms and in the mid 20K ohms.
> 
> ...


Yes, I tried with the kill wire disconnected, but no spark. Magnet is very strong. I checked the ohms between 2 spark cables and it measured at 33K. Have replaced the original coil as the new coil did not solve the problem. The new was also a Kohler original part but somehow the connector bold holes were on opp ends and so I had to invert it to mount. It is off again anyhow. Not sure where ro go from here. Now, after 100 attempts, the switch wont turn the flywheel, so had to by pass the solenoid. Tried a new ignition switch but that did not solve the issue. Hqve ordered a new solenoid. Will also try to take a resistance reading as specified in the Kohler manual. So far have just been checking across both spark cables.

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## FredM (Nov 18, 2015)

this is an absolute Lulu mate!!, there is something simple not happening, with that kill wire removed from the coil body, the ignition module is isolated from the rest of the electrical system and the engine should start, it is strange that the engine originally run earlier until you changed fuel pump, doing this should not have come into the equation of no spark.

trying to work out how the mount holes on the ignition coil were on the opposite ends, and you had to invert this to mount the module








Ok, I can see how the coil mounts now, the mount holes are offset so the coil can only mounted the correct way.

as silly as this sounds, can you check for an earthing path from flywheel to crankshaft with your multimeter, I mentioned earlier about checking for a circuit between the module soft iron body to engine and this is the last area I can think of that would break the circuit.


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## jhngardner367 (Apr 5, 2011)

Disconnect the oil level sensor,and try it .


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## Kenny z (7 mo ago)

Did you ever discover the problem? I have same on Gravely promaster 18 h lawn mower. Changed every electrical component except safety switches.


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## pogobill (Jan 31, 2012)

Kenny z said:


> Did you ever discover the problem? I have same on Gravely promaster 18 h lawn mower. Changed every electrical component except safety switches.


I hope so, the post is quite old. You may want to start your own post and describe what you've got so far.


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