No spark again

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  #1  
Old 04-26-11, 10:22 PM
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Angry No spark again

I have 3 partner concrete saws I bought not running. My plan was to fix them and sell 2 and keep one. Anyways about a year ago when I bought them I couldnt get spark on any of them. Sometimes it would have spark and most of the time they wouldnt. I was away from home for a while and just got back so I started to dink around with them again. I reset the gap between the flywheel and the coil and it had great spark. I put it together and it had spark, fuel and compression but wouldnt even fire once. I checked the spark again and nothing. Is it common for these ignition coils to fail like this where they make a spark and then dont work? It drives me nuts and wears my arm out.

I have the wire pulled off to the coil that goes to ground so I know thats not the problem.
 
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Old 04-27-11, 07:55 PM
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Have you tried a different plug? ___________
 
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Old 04-27-11, 08:53 PM
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Would a plug have a problem that would cause this? Im not sure if I tried another plug the first time but Ill try it tomorrow.
 
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Old 04-28-11, 05:21 PM
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Yes, especially asian spark plugs.
 
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Old 04-28-11, 07:59 PM
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I didnt get a chance to check it today, Ive been playing around in a septic tank for 2 days. I should have some time tomorrow.
 
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Old 04-29-11, 08:50 PM
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I checked it out today, the sparkplug doesnt make a difference. It does make electricity just not enough to make a spark. I take it that means the coil is junk? I put on a different coil off another of the saws and it does the same.
 
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Old 04-29-11, 09:30 PM
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I wouldn't think all the coils would be bad or fail the same way. Could be wrong, but maybe the mounting areas are rusty, the gap is wrong, or something...
 
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Old 04-29-11, 09:34 PM
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I'll clean everything up tomorrow, I couldnt find the other coil. Ill find it tomorrow and try all 3. Maybe try another saw.
 
  #9  
Old 04-30-11, 07:55 PM
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Well I cleaned everything down to bare metal so its grounded good and it didnt change a thing. I tried all 3 and they all do the same.
 
  #10  
Old 04-30-11, 08:05 PM
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when you say it has electricity, but not enough to make a spark, how are you determining it has electricity? Are these the two stroke, hand held concrete jobs?
 
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Old 04-30-11, 08:23 PM
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They are the 2 stroke concrete saws. They are all Partner K700. If I hold the end of the sparkplug wire and touch the engine I can feel a little electrcity.
 
  #12  
Old 05-01-11, 08:44 AM
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If you're spinning the engine over fast while you hold the lead wire from the coil and your hand isn't shocked numb, you have a bad coil/module.

You need a couple of fast passes on the coil by the magnets to saturate the coil windings to get the voltage for a spark. For instance if you hold the lead wire while moving the flywheel magnets back and forth by hand you'll get a tingle and the coil may be good.
 
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Old 07-28-11, 06:27 PM
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I bought a brand new coil for these saws and still no spark, could the magnet in the flywheel be weak? The new one does the same thing.
 
  #14  
Old 07-28-11, 07:30 PM
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No the magnets would only go bad if subjected to alot of heat - like from a torch. Normal engine heat won't wreck them. You can demagnetize by other means, but the magnets aren't likely to be bad. A new module can be bad but It's more likely the way you're testing it or with the way you have it installed.
 
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Old 07-29-11, 07:59 AM
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The magnets seem strong enough to me. I stuck the allen wrench on them and they stick together pretty well. Im at a loss with this. Maybe Ill send some pictures.

Buying a bad coil doesnt surprise me the way my luck goes.
 
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Old 07-29-11, 09:50 AM
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Heres a picture, you can see the allen wrench stuck on the magnet. Im starting to wonder if the new coil is bad.

I had the same problem on a VG4D wisconsin and a electrical place that rebuilds magnetos said over time the coating on the wire inside the coil breaks down and they go bad.

 
  #17  
Old 07-29-11, 01:23 PM
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Yes, an old coil can certainly go bad. Leave everything in place like you have it, take out the spark plug, stick a screwdriver in the spark plug wire. Then move the magnets just before the coil pickups. Hold onto the screwdriver and rotate the flywheel magnets completely past the coil, back and forth. See if you get any tingle from the screwdriver.
 
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Old 07-29-11, 01:52 PM
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Originally Posted by marbobj View Post
Yes, an old coil can certainly go bad. Leave everything in place like you have it, take out the spark plug, stick a screwdriver in the spark plug wire. Then move the magnets just before the coil pickups. Hold onto the screwdriver and rotate the flywheel magnets completely past the coil, back and forth. See if you get any tingle from the screwdriver.
I just did this, I had one finger on the end of the plug wire and another finger on the engine. I moved the flywheel back and forth as fast as I could. I felt a little tingle but not much.
 
  #19  
Old 07-29-11, 03:35 PM
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If this is with the new coil, the coil is likely OK. Make sure the gap between the coil and the flywheel is OK - about .010, dump all the gas out of it, spin it over about ten times without the plug in it and the throttle wide open. Then put a tablespoon of fuel down the plug hole, install the plug, then half throttle, no choke, pull it over a few times to see if it will fire. If it's semi flooded it may take a few pulls.
 
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Old 07-31-11, 09:04 PM
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Originally Posted by marbobj View Post
If this is with the new coil, the coil is likely OK. Make sure the gap between the coil and the flywheel is OK - about .010, dump all the gas out of it, spin it over about ten times without the plug in it and the throttle wide open. Then put a tablespoon of fuel down the plug hole, install the plug, then half throttle, no choke, pull it over a few times to see if it will fire. If it's semi flooded it may take a few pulls.
Nothing, checked spark and nothing
 
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