1970 14 hp kohler no spark

wayne huber

New User
my 1970's economy 14 hp kohler has no spark it has pointless ignition the wire from the stator to the a side of the trigger should that wire have power when you turn the key switch on ???
 
The wire to the key switch is a "kill" wire and should NEVER have power from the ignition switch, or you will let the very expensive smoke out of the EI module.

The EI is self-powered by the action of the magnets on the flywheel and the coils on the stator behind the flywheel..

Troubleshooting info is in the Kohler factory manual at the link below: (.pdf format)
K series single cylinder
 
I also have a 1970 Power-King that had the breakerless igniton system.
When I found out how expensive the parts were I converted it over to battery ignition with points.
Usually when I work on a Briggs engine I switch them to electronic ignition, the price of a coil is less than points, condensor and the agravation of the points fouling.
I have several PKs to sell.
 
As Bob said trigger module is powered by a seperate winding on alt stator & lead(s) to trigger module should only have AC voltage when cranking eng.

Before condeming trigger module/coil try a couple of things 1st.

Locate & disconnect ign kill lead to ign sw at Y/T connector close to ign coil connection,crank eng & check for spark,if you have spark now then problem in lead to ign sw,ign sw itself or safety sw's on tractor(if any).

If still no spark with kill lead disconnected,disconnect AC output leads from alt stator at rectifer/regulator,crank eng & check for spark,if you have spark now then problem in rectifer/regulator,depending on how tractor wired,if output from regulator is wired thru ign sw,if diode(s) in regulator shorted when ign sw turned on this will allow DC battery voltage to backfeed into alt stator & turn same into an electromagnet killing all AC voltage in alt stator.

If still no spark with kill lead/regulator disconnected,then download/save K series service manual at link provided by Bob & follow troubleshooting guide in sect. 8 of manual for solid state ign.
 
Thanks guys for your feed back !! I went back and did the inspection as per the kohler service manual so I started at the stator I have 23 volts when cranking at the a terminal of the trigger mod . So I then bench tested the trigger itself it looks good as per the test then I did a bench tested the coil with a ohm meter witch seem to be good so I unhooked the kill wire from the switch and still no spark !! so I the took my test light and hooked to the connector at the bottom of the coil and I do get a dim light when cranking at the coil trigger wire. I really think its a bad coil !! but at $225.00 would like to be sure!!
 
Remove coil from eng & take with you,fri-sat check with several local mower shops to see if they have a coil tester that they can test coil with,some shops have a tester for this type coil,others don't.In the meantime if you haven't done so already,check plug lead with an ohmmeter,you might have a bad plug lead,also use a new plug for testing as old plug may be bad.

If local shop can test coil & same is bad,kohler online parts lists coil for $193 if that's any help.

One thing that confuses me in you reply,when you said you disconnected kill lead at sw,do you mean you disconnected kill lead where output from trigger module & coil join OR at ign sw itself?
 
unplugged the wire at the ignition switch to make sure my switch was not bad. and I did check the plug wire its good . I have a in line spark tester so I can see it flash when I get spark I have the coil with me so I can check with a few places to see if anyone has a coil tester. thanks again for your feed back!!!!
 
Interesting. IS there a machine out there that can definitively test this which, as you know, has diodes, a capacitor, and probably some other electronic components in it?
 
Disconnect kill lead wire at junction of trigger module/coil also & check between each end of same with an ohmmeter unless you can see length of wire completely between eng connection/ign sw,wire may be grounded due to yrs of heat,vibration & rubbing against sheetmetal or brackets on tractor,if wire grounded it will give same result as turning ign sw to off/stop position even though kill lead disconnected from ign sw.
 
Bob-I think you misunderstood my reply,I was speaking of coil which to my knowledge has no electronic parts in it except possibly an internal condenser as looking at diag on pg 8.4 in manual of trigger module the condenser is located down stream of kill sw & I know of no ext mounted condenser on this type of ign system & suspect condenser is internal in coil,this might also explain why manual only tells you how to check secondary of coil,but nothing about checking primary.

It's possible there are either old testers/newer testers running around out there to check trigger module operation without removing trigger from eng in addition many of newer kohler eng have smart spark system which have a pickup installed in coil,when this style coil is checked I don't know if different make/mod testers have provisions for checking pickup also when testing coil & possibly be backward looking to check trigger modules,it's been over 30 yrs since I've taken a coil to a shop to have checked so I don't really know what's out there now in the way of testers.
 
Yep, no diodes, I see, but a capacitor in series with the primary winding. I wonder what the results are when checked with a Mercotronic... can it be tested as a normal coil with that capacitor in series?
 
If the the condenser is internal in coil which I more & more suspect,it probably serves the same function as a condenser in a normal points ign setup in that when points open a spike voltage up to 3 times supply voltage is generated for a fraction of a second as magnetic field in coil is collapsing,this spike voltage is induced into secondary winding of coil & boosts hv output,in addition spike also traveles back to source(points)the condenser across the points absorbs the spike voltage & reduces voltage in coil primary to as close to zero volts as possible before the next points cycle so you get max voltage buildup in primary of coil next time points close,in addition condenser prevents point burning/drawing an arc when points open,if condenser wasn't in circuit or if condenser open/shorted voltage would stay high in coil primary & have the effect of points staying open/closed all the time & no high voltage will be generated.

As far as solid state ign,I think the condenser in series with primary of coil is there to function as a buffer to protect scr in trigger so spike voltage from coil doesn't exceed piv voltage rating of scr,it may also function as a disconnect on load side of scr as usually when you use an scr in a DC circuit circuit when the scr turns on it will stay on an act as a latching relay till source voltage or load disconnected from scr so same can turn off,I found this out the hard way many yrs ago when I added foil defroster grid to rear window of my van,instead of buying a electro-mechanical relay I used a 20A solid state sw I had on hand,I killed battery in van 3 times in 2 days & couldn't figure out why,came to find out soild state sw was staying on/latched & powering defroster grid all the time after solid state sw turned on,even though sw on dash for sw turned off,only way to turn sw off was to disconnect load/supply voltage for a second or two.

As far as checking coil with a normal coil tester designed for 12v coils I don't know,it's something that would have to be tried,with condenser in series with coil primary if condenser open tester wouldn't work on coil,if condenser shorted it may give a false indication as to condition of coil or if coil working correctly,the only way I can think of to test solid state coil is to take a know good coil & see how/if it works with tester & use that as a standard when checking other coils.

Years ago I gave a thought to building a tester for trigger module/coil,however since that time either I no longer have engines with solid state ign or converted same to point ign as solid state systems went bad,just converting is an adventure in itself.
 
Actually, I believe the capacitor in those Kohler EI coils gets charged voltage from the stator that gets rectified by diode(s) in the trigger module, and when the SCR is triggered it discharges the capacitor through the coil and makes the spark, a primitive CD ignition system.
 
You may be right,I've never put a trigger module on bench & tried to do open heart surgery on it & figure out how it works,what does strike me as strange is condenser is non polarized,I would think same would have to be polarized to operate correctly in a cd system,but I may be/am probably wrong,it just may be another one of those mysteries of life/electronics.
 
HOW do we know the capacitor that's epoxied inside the coil is NP?

I've got a bad coil lying on the back of the bench somewhere... I'll try to find it and dissect it some cold and stormy day this winter when it's too cold to do much else!
 
Hi guys I went and retested my stator and found that I'm only getting 2.3 volts from it when cranking to the trigger mod and at the bottom of the coil !! How much should that be !!! Nothing in the kohler service manual states this .or should it be 14 volts like the alternator?
 
I'm just going by symbol used in trigger module/coil drawing,the way condenser symbol drawn would indicate a non polarized condenser as there is no pos(+)end,the symbol is the same as a symbol for a condenser used in AC circuts for motor start condensers,line filters etc which are non polarized.
 
I no longer have any eng with solid state ign,maybe one of the other guys knows/can help as to what approx voltge is to trigger module when CRANKING eng,the 14V you're talking about from stator is when eng running,the alt output voltage is dependent on eng speed,if you have a weak/tired battery,wiring on tractor in poor condition,starter motor that's getting tired or summer wt oil in eng below 40 deg all will affect cranking speed/voltage output from alt stator.

If you have been reading/following replies and as stated in replies if you haven't done so already,disconnect ign kill lead at BOTH ends & check between either end of wire & chassis/eng with an ohmmeter to confirm kill lead not grounded,then disconnect AC stator output from rectifer/regulator & crank eng/check for spark,shorted diodes in regulator will cause loss of or low AC voltage in alt stator if diodes bad.
 
(quoted from post at 16:04:45 11/25/13) my 1970's economy 14 hp kohler has no spark it has pointless ignition the wire from the stator to the a side of the trigger should that wire have power when you turn the key switch on ???
Good morning Joe I read your feed back. I did unhook and check the kill wire. the battery is brand new and was replaced before it lost spark and ran good. the tractor was being used and stop running like someone turned the key off ! I did repair the wire from the stator to the a side of the trigger. The insulation was coming off and was afraid of it shorting out !! the stator at that time was inspected and no burn marks or damage was seen. Tested the stator had good readings from the two leads going to the regulator but no reading from the 3rd wire that goes to the trigger. I need to test it like you said with the regulator leads unhooked when I do I will let you know what I get. Again I thank you for your help !!! and Joe so you know we have owned this tractor since 1973 and has always parked this tractor inside when not being used . This tractor is like part of the family! Thanks again.
 
(quoted from post at 16:10:35 11/30/13)
(quoted from post at 16:04:45 11/25/13) my 1970's economy 14 hp kohler has no spark it has pointless ignition the wire from the stator to the a side of the trigger should that wire have power when you turn the key switch on ???
Good morning Joe I read your feed back. I did unhook and check the kill wire. the battery is brand new and was replaced before it lost spark and ran good. the tractor was being used and stop running like someone turned the key off ! I did repair the wire from the stator to the a side of the trigger. The insulation was coming off and was afraid of it shorting out !! the stator at that time was inspected and no burn marks or damage was seen. Tested the stator had good readings from the two leads going to the regulator but no reading from the 3rd wire that goes to the trigger. I need to test it like you said with the regulator leads unhooked when I do I will let you know what I get. Again I thank you for your help !!! and Joe so you know we have owned this tractor since 1973 and has always parked this tractor inside when not being used . This tractor is like part of the family! Thanks again.
Well guys I unhooked the regulator wire and check check the voltage again and still had 2.3 volt at the a side of the trigger ! I feel this is not enough to energize the coil to make spark. I feel I need at least 10 volt ! let me know if you agree !!! So I was able to talk to a guy at kohler tec support. He remembers working on the trigger type ignitions in his younger days . With all the information available to him he could not find any information on the voltage needed from the two stator windings to power up the ignition . But we both agreed 2.3 volts was not enough !! So the stator is no longer available and not repairable far as I know. SO , I wonder if a guy could hook battery voltage to the a side of the trigger and make the ignition work !! And the key would be used as a ground and turn the power off to the ignition!! Let me know what you think !!! You guys have been a lot of help and I thank you!! Happy holidays !!!!
 
I do NOT believe there's a way to operate the module by powering it b y battery voltage, and such an attempt will "let the smoke out", if in fact it IS still functioning.


Here's MY interpretation of how this system works, FWIW. Did you check AC voltage out of the stator with the trigger module unhooked from the stator? The way I understand this system, the stator makes AC, the trigger module rectifies it to DC, which is stored in the capacitor built into the coil.

When the tab on the flywheel passes the trigger, an SCR is "fired", which rapidly discharges the capacitor in the coil, causing current in the coil primary that is "stepped up" by the turn ratio to a high enough voltage to fire the spark plug. (A type of "CD" ignition.)

The open-circuit AC voltage out of the stator would be one thing, beyond that (whatever the correct value should be), the diode(s) in the module have to be OK to make the DC voltage, the SCR must not be shorted or leaky, and the coil and capacitor must be functioning so a DC voltage builds up between spark events so the coil is able to be fired.

So, if you are measuring DC voltage at the coil terminal and it's actually low, the fault could be in the stator, the trigger module, or the coil.

Are you aware most likely you CAN install a plunger and a set of points and a coil and convert it to Kettering ignition? (Seems to me certain blocks were not drilled for the plunger or point mounting holes. Normally, the holes are there and the plunger hole is plugged with a little "cup plug".

If you GGOGLE "Kohler 237750S" you will get info on what is involved.
 
(quoted from post at 17:04:32 12/03/13)
(quoted from post at 16:10:35 11/30/13)
(quoted from post at 16:04:45 11/25/13) my 1970's economy 14 hp kohler has no spark it has pointless ignition the wire from the stator to the a side of the trigger should that wire have power when you turn the key switch on ???
Good morning Joe I read your feed back. I did unhook and check the kill wire. the battery is brand new and was replaced before it lost spark and ran good. the tractor was being used and stop running like someone turned the key off ! I did repair the wire from the stator to the a side of the trigger. The insulation was coming off and was afraid of it shorting out !! the stator at that time was inspected and no burn marks or damage was seen. Tested the stator had good readings from the two leads going to the regulator but no reading from the 3rd wire that goes to the trigger. I need to test it like you said with the regulator leads unhooked when I do I will let you know what I get. Again I thank you for your help !!! and Joe so you know we have owned this tractor since 1973 and has always parked this tractor inside when not being used . This tractor is like part of the family! Thanks again.
Well guys I unhooked the regulator wire and check check the voltage again and still had 2.3 volt at the a side of the trigger ! I feel this is not enough to energize the coil to make spark. I feel I need at least 10 volt ! let me know if you agree !!! So I was able to talk to a guy at kohler tec support. He remembers working on the trigger type ignitions in his younger days . With all the information available to him he could not find any information on the voltage needed from the two stator windings to power up the ignition . But we both agreed 2.3 volts was not enough !! So the stator is no longer available and not repairable far as I know. SO , I wonder if a guy could hook battery voltage to the a side of the trigger and make the ignition work !! And the key would be used as a ground and turn the power off to the ignition!! Let me know what you think !!! You guys have been a lot of help and I thank you!! Happy holidays !!!!
Yes Bob I did check it with the trigger unhooked and tested it at each point to the coil getting only 2.3 volts at each point. We may end up butting the conversion kit on . But I would still like to figure out the problem.
 
I have repaired a few over the years... this is ONE case where it"s handy to have a set of known-good parts to substitute.

I have a good stator somewhere in the shop, if I can find it, and have another on a 140 DEERE that was converted to Kettering ignition "cuz the module failed. That one needs an OH and will have to come apart (a couple possible sources IF you determine it"s the stator and cannot find one).
 
I found a stator in shed removed from eng(s)that I did point conversion on & removed stator when I scrapped eng.First thing to check,if you had to tape trigger lead,check lead all the way back to stator,lead may be shorting to bearing plate or in clamp to hold wires to plate.

Next check resistance of coil for trigger module on stator,with trigger lead disconnected,read between lead & eng block/stator frame,my coil read .45 ohms(less than half an ohm),I don't know if this is correct or not as I didn't confirm what ign problem was with solid state ign,if Bob can find his stator or by you checking you're stator you may be able to confirm if .45 ohm is correct.

If the .45 ohms is correct & reading less than that possible causes could be trigger lead shorted to bearing plate,wire turns in coil shorted together or coil shorted to stator frame.Other possible cause of low voltage,magnets in flywheel missing/cracked.

If you are considering doing a point conversion be sure you know what you're getting into & do some checking BEFORE buying conversion kit & also ask yourself if you have elect knowledge/skills to do conversion as this is NOT just a 15-30 min job of slapping points,plunger,coil & condenser on eng & job done & you can walk away from it.

First thing as Bob said check on left side of cam gear cover to see if you have a series of 4 vertical tapped holes in block,if you don't have holes you can't do conversion,early factory conversions had holes,later eng with solid state ign didn't,next check flywheel cover for a hole/plug in hole or bearing plate for a hole/plug in hole in area between starter/block,you must have hole in either location in order to time ign after doing conversion either by static/timing light method,many of later solid state eng didn't have holes in either location due to ign timing being fixed.Next you'll have to decide after driving dowel pin/cap into eng for point plunger if you want to pull oil pan & remove pin/cap from eng or take your chances with same in pan as many of us do,instructions included with kit recommend removing pan.

Next check existing ign sw if same has a terminal that provides +12v when sw in on/run position,due to fact sw designed for magneto/solid state ign sw may/may no have terminal depending on how tractor wired & acc on tractor.If oem sw doesn't have a terminal for 12v supply you'll have to buy a new ign sw designed for battery ign,after that you'll still have to provide a +12v source to coil when cranking eng by either changing starter sol to a ford style sol,add a push button to dash or add an aux relay if replacement ign sw doesn't have an ign terminal that +12v is provided to while sw in on/run position & start position.
 

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