Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I turned the key on and have no spark from the plug or even the plug wire when turning over the engine

How do I know if it is the coil magneto or the xstar module magneto?

It is a model 38180

Below is the 38180.  Blow that is the 38185, no XStar.  ??  Note the XStar has one lead.  The primary splits and would go to ground and the other wire probably to an on/off or kill switch.

 

well i think where making this diagnioses a bit complicated.....lots of good info given which is good but also complicates things alot!!... the system is very simple to diagnose... no mutli meters required... like i mentioned before make sure u have a good connection on the "red wire" to ground....disconnect the kill switch.....and since u had the coil off my sure it gapped at .010-.012... and if u have a adjustable spark tester set it to at least a 1/4 gap...then test...if theres no spark the coil is no good... no more testing needed...

as far as adding a aftermarket module which is fine when your replacing it on a points system (i have used ALOT of these modules with 100% success) ...but when your installing it on a magneto coil (electronic) the module is inside the coil so if the module inside the coil go for a $#%*, then the wire coming outta the coil (red wire) is just the ground for that module inside (which is also connected to your kill switch)...so if the module "(switch)" in side the coil get stuck ON then u can add an aftermarket module kit and it will work..although if the module "(switch)" becomes open (no connection) then an aftermarket module will not work.. hope this makes sense...

Thank you guys for all your input!  This dog gone thing has become somewhat of a quest.  Like I said earlier, I hate to throw away a good machine.  I have seen a coil/module combo on ebay for about $75.  That would be my final effort.

Here is the latest that I have done.  As I stated, last week I bought a used coil.  I also bought a mega fire II ignition module.  The other day I installed everything and got good spark. I then put it all back together and it ran for 30 seconds and quit.  Thats when I started posting on this forum.  Following all these wonderful suggestions for you guys that have donated so much of your time, I carefully cleaned all connections real good.  I took some fine emery paper and lightly sanded all areas that had electrical to metal connections.  I also took some lacquer thinner and wiped all dirt and dielectric tune up grease I had applied to any connections.  I did this thinking that it may have some how been forming some kind of barrier.

I should re-iterate that the flywheel has 3 MAGNETS on it.

Tonight I reinstalled everything and gaped the coil with the recommended business card.     Wire was installed from coil to mega fire II ignition module.     Wire then installed from ignition module to good ground.    NO SWITCH WIRED IN AT THIS TIME.     I then filed and cleaned an edge of an engine cooling fin to hold the spark plug against.    I plugged in the electric starter and while holding the spark plug against the filed cooling fin, I got INTERMITTENT SPARK (although I did not get "zapped" when holding the plug wire).  It would spark for a few seconds quite aggressively and then stop sparking.   It sort of looked like a big thick spark.  Sort of bigger than a normal spark you would see.   Returning say five minutes later, it would spark again and then stop sparking.   I have the plug gaped at about .030-.032. 

Unfortunately I do not know what to guess at this point.  Perhaps the module.   Since I am getting a real good spark now, I am leaning towards the module and not the coil.  Could a coil throw an intermittent spark?    Perhaps I should buy a different aftermarket module?

Hopefully it posts, but below is a photo of the exact setup as removed from the engine of this 38185  sn 2001010.  Notice the module in the photo.  Brand new that baby goes for $125 +.  This is the one I replaced with the mega fire II.

broncman wrote:

ok pictures are good:))..... with that setup in the picture its wired exactly the same way with the replacement module... so the wire coming from the coil goes to the POSTIVE side of the replacement module and of course the other goes to ground side... now personally i would NOT use a business card as a measuring tool becuase business cards vary in thickness alot...and lve repaired more than a few coils gaps being out of adjustment in the past from customers using business cards...i did one this summer that had a gap of .045.. customer said he was told to use a business to gap it... bad idea that machine would not start...all i did was re gap to .012 and it started right up.... so its important to get the right gap set.. set the gap at .010-.015..

as far as having spark then it stops is unusual...maybe your replacement module isnt working properely??...but first get the gap within spec..then if no change i would try another module..

i was just reading up on these modules.... and aparently they will work on 1 or 2 magnet flywheels.... so if yours is has three thats most likely going to be a issuse... need to read more havent ran into this issuse before...of cousre i cant remeber if ive ever installed a module on a three magnet flywheel before... hmmm something to be concerned with for sure..

If you don't have feeler gauges, a sheet of paper is often about 0.003-0.004" thick. You could try a few sheets of paper to try for a 0.012" gap. You could also temporarily try setting the spark plug gap really small (maybe 0.010") just to see if the spark became more consistent.

>>>Could a coil throw an intermittent spark?   

    Yes.  Can happend with a small open in the primary winding.

>>>Perhaps I should buy a different aftermarket module?

    No.  Without a reading from ground to the spark plug end of the coil other parts won't make any difference.  The coil is defective.  If a new module does then your meter is defective. 

    The coil secondary is a single wire from the sparkplug end, wound many times around the iron core then to ground.  The reading you should get from the sparkplug end to ground is 5800 to 7940 ohms.  You get zero and intermittant spark.  That indicates the coil is defective and has a break in the coil wire.   Since your getting intermittant spark the spark is juming the open sometimes and sometimes it dosen't.  That happens at times and not unusual.  The induced voltage is very high and jumping an open not that difficult. 

    A possibility that give the symptoms is a bad connection from the primary coil to the sprk plug hood.     

If the coil is going to be junked anyhow, could he maybe try cutting off the wire that goes to the plug, near the coil, and replacing it somehow? If it's just 1 layer of insulation (does not also have a shield around it or something), could a small area of insulation be stripped off near the coil, then the wire checked for continuity to the plug while wiggling the wire? That might be a way to see if there's simply a break in the wire?

Hello guys;

I think I will just bite the bullet and contact/order from the guy on ebay who has the coil/module as a set.  I have ordered from him before and he is reliable.  This will be my last shot.  If it does not work, then I will tell my buddy his machine is dead.  I will then take the machine apart, list on ebay, and try to recover my losses.  I'll let you know what happens.  THEN, I will try a little disecting of one of the bad coils!

Broncman,

    Last night I went through some known good SSI coils and got no reading between ground and the end of the secondary.  Very puzzling.  After many hours of poking around it occurred to me that the boot end may not touch the primary wire but be close enough to be jumped by the spark.  That’s the case.

 

    By connecting an alligator clip to the kill tab on the coil (not the iron legs) and the other end to the boot end I could grab both the boot and the primary wire and twist them.  All the coils got a reading and most took a good deal of force to get it.  Five know good SSI coils would not give me a reading without forcing it.  By the way since the first five I pulled out all did the same thing.  It makes me think this is very common.

 

    Your coil may be good and as mentioned in the prior post and just be the boot connection.  It could also be a leak on primary wire to the engine. 

 

    Try the above and if it does not work Ed Stoller suggested this which I’ve never done.  Rip out the primary wire from the coil body.  Clean in there then try to get a reading.  If you don’t then the coil has an open.  If you do there should be a brass nail in the body the coil wire goes onto.  Solder it if you can.  Ed says that’s possible but I don’t see how as I think the insulation would be in the way.  Regardless get a new wire or test your old wire and install. 

 

    If you end up skunked it looks like your plan of ebay would take a while and tie up money.   The expensive coil is in scads of snowblowers and many more lawnmowers.  You could put it aside and wait for a clunker lawnmower to fall your way.  Shops have old mowers and Craigslist guys have piles they post about.

 

   Also, if your coil does get a reading (either of them) you still had intermittent spark.  The symptoms you described can happen with reversed polarity on the Magafire.  I don’t see how but guys have mentioned getting intermittent spark then changing polarity and the engine ran fine.  That’s one possibility.

 

    Another is weak magnets.  Briggs says the magnets should be strong enough to hold and no 10 flat head screwdriver to the magnet.  If your magnets went iffy they could be a problem.

 

    Just say your good coils went bad.  That may have been due to the three magnets.  ??  Before buying another coil you may want to give it a breather and think about all you’ve done before possibly blowing another coil if that’s what happened. 

 

    Which brings up that last point.  Your model and serial number machine does not have an SSI or Xstar per Toro drawings.  What’s the model number of your engine?