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AnsweredHot!Tecumseh LV195EA 6.75 hp. No spark

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a095781
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2017/08/20 10:04:00 (permalink)
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Tecumseh LV195EA 6.75 hp. No spark

Craftsman mower, Eager 1 , engine #143.016702.  Friends' mower.
Doesn't have many hours and been sitting for , who knows how long. Water in intake.   No fire.
Totally disassembled engine, honed scratches out of cylinder, lapped valves, new carb. , new mag. coil, new plug, flywheel magnet is good.   Plug gap .030, mag. air gap  (tried everything from .006 to .060) , cleaned mounting posts for mag. laminate core  (0 ohms between coil core and plug hole in head).
Have never seen this before but there is no spark generated from coil to plug. I tried the O.E.M. coil # 34443D and the replacement coil #Stens 440.505. Timing marks are lined up on cam.    >>>>>  No spark. <<<<<<
Has anyone ever experienced this weird situation or have any idea why this thing will not spark?
post edited by a095781 - 2017/08/20 10:08:54
a095781
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/08/20 10:07:09 (permalink)
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Late note:  Timing marks on cam are lined up.
Roy
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/08/20 11:37:38 (permalink)
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Did you try it with he primary wire disconnected from the coil? The problem may be in the switch.
a095781
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/08/24 08:24:31 (permalink)
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Disconnected the kill wire, first thing.  All mounting points of contact are clean and dry.  Have never seen a lack of spark on a simple magneto ignition.  There has to be a reason/solution. Everything I new and/or functioning except the spark.
Roy
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/08/24 11:50:53 (permalink) ☼ Best Answerby a095781 2017/08/24 18:02:23
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I am not trying to be a schmartash but is the coil mounted right way up? Don't laugh, I have seen it happen.
a095781
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/08/24 18:09:29 (permalink)
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Mounted the same as the original.  Spade connector on bottom (engine side) and primary wire coming out of top of coil.  Only way I have seen them mounted.  All pictures of the coil show them mounted that way.  I'm on 3rd coil and still no spark or even an indication of any voltage on a meter.   Very odd.  Thought there may be an odd quirk with the coil, or something.   Believe me, I've searched everywhere for a solution.
Roy
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/08/25 12:14:08 (permalink)
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Look at the coil, the leg should be stamped 'THIS SIDE UP'. If it is correct the only thing left is the flywheel.
a095781
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/08/25 13:55:44 (permalink)
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Thank you Roy, for your help.
Nothing marked on new coils. Stamped on old coil and installed new coil same side up.
Only difference in coils is the resistance from spark plug terminal to the coil ground/laminate.  Old coil reads 4kOhm,  2 new coils only read about 1.8 K Ohm. None of them spark.   Magnet is good in flywheel and I tried a different flywheel.  Unexplainable.
Mikel1
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/08/25 14:58:45 (permalink)
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How exactly are you checking for spark?
a095781
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/08/25 20:25:09 (permalink)
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Checking for spark, every possible way.  I try turning flywheel by hand. No spark.  I have a large 1/2" drill with a 7/8" socket that I turn the flywheel with at about 200 R.P.M.  No spark.  And, I put the voltmeter on the plug wire when I turn flywheel to check for any surge.  Nothing.  Have never had a magneto failure like this one.  Tried mag. air gap from .006  to .020 and no spark.  New plug gapped at .030, no spark. Tried 2 flywheels, both with good magnets.
Has to be grounding out somewhere but there is no place left.
a095781
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/09/03 06:27:06 (permalink)
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Appears replacement coils are too weak to operate ignition system.  Re-installed the old, O.E.M. coil and I can get a spark. Not a great one but it is a spark.   Only conclusion is that the new, replacement coils do not have the same amount of turns of wire in their coils.  This explains the difference in resistance between the coils.  O.E.M. coil has almost 4K impedance through coil.  Replacement coils only have about 1/2 that resistance, meaning there is approx. 1/2 the coil windings in the replacement coils than in the O.E.M. coils.  That equates to "Spark across plug gap".
AVB
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/09/03 10:46:23 (permalink)
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That can explain it but double check that you are using a non resistor plug. J19LM or CJ8
 
As for the speed of the flywheel for magneto coils it needs to be at least 300 rpm for spark to occur. Some older coils would trigger at slower speeds. The Briggs service manual specs their Magnetron coils at 350 rpm minimum.
a095781
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/09/03 12:20:05 (permalink)
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Brand new J19LM plug. Non-resistor.  .030 gap.   Everything perfect except spark. A good mag will spark when hand turning the flywheel.  Using a variable speed drill to turn flywheel so I have had it over 500 R.P.M.  Old coil sparks at less than 100 R.P.M.   I have to conclude that the 2 replacement coils are too weak.  Have to spend the $40.00 for a good one, I guess.  Not going to do that until I get some specs. on them though.  Most confounding small engine problem I have ever had.
 
Thanks AVB 
AVB
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/09/03 13:46:45 (permalink)
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With Chinese junk making it way into the market like it has anything is possible. Don't take me wrong some of the parts are better but there is more junk than good out there.
 
Good luck on getting someone to actually check their parts. Here lately I have been having terrible time with aftermarket belts from my normally good supplier. The specs just keeps jumping all over the place. With MTDs being so picky about their belts I had to go back to buying and installing the OEM belts on the customer mowers.
 
It does sounds like you finally found the root cause the problem so best of luck getting the right part now.
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Re: Tecumseh LV195EA 6.75 hp. No spark 2017/09/03 18:46:28 (permalink)
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Agree with the Chinese junk but sometimes, you can get a good product.    Had belt problems with Sears and Cub Cadet.  I shopped "V Belt Supply" and am very happy with their products.  I need 94" and 120" A belts and V Belt sells comparable belts for about 1/3 rd the price.  They may not last as long as some O.E.M. parts but, for the price you can use 3 to 1.   I getter better service on my Sears 4' riding mower out of the V Belt products.  Haven't worn out  a Cub Cadet belt yet.
 
Perpetual, on-going battle with small equipment and it's spreading to larger equipment.  Nothing like 20 year old machines.   I like old, like me.
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