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Model: OH195EP

Tilling fine yesterday, turned it off and it was stone dead this morning -- apparently no spark, no start. I have a garden to get in!

It looks like accessing the coil will be a major undertaking, but once I get to it, how can I most easily test it to see if it's dead or if the problem is in the magneto?

It should look like this -- a spade fitting, the spark plug cable and that's it:



I have most electronic testing devices.

Thanks for any advice.

Golodkin said:

Model: OH195EP

Tilling fine yesterday, turned it off and it was stone dead this morning -- apparently no spark, no start. I have a garden to get in!

It looks like accessing the coil will be a major undertaking, but once I get to it, how can I most easily test it to see if it's dead or if the problem is in the magneto?

It should look like this -- a spade fitting, the spark plug cable and that's it:

View attachment 43650

I have most electronic testing devices.

Thanks for any advice.

Click to expand...

The first thing to verify is that the shutdown wire (the spade) is not grounding out somewhere (chafing, etc.). Otherwise, what you pictured is typically all there is - no other parts in play unless it is very old and still has points (well, other than the magnet inside the flywheel).

tadawson said:

The first thing to verify is that the shutdown wire (the spade) is not grounding out somewhere (chafing, etc.). Otherwise, what you pictured is all there is - no other parts in play (well, other than the magnet inside the flywheel).

Click to expand...

So I would have thought, but look at this exploded diagram. That looks for all the world like a rotor/stator arrangement with leads off the stator. Yes? No?

If no, what is that #315 thing?



I'll of course check the kill wire when I'm able to get to it, but so far I'm stumped by getting the housing over it loose from underneath the gas tank. I can see the coil, but can't get to it. Odd arrangement!

Thanks!

315 is a stator for DC aux poer for lights and such, and has nothing to do with ignition. Not sure why that would be on a tiller, but then again, you might not have the exact diagram for the engine you have, and may find that stuff isn't there on yours.

Looking up "OH195EP" I find no less than 25 or so variants . . . without the rest of the model number, the specific parts list cannot be found.

tadawson said:

Looking up "OH195EP" I find no less than 25 or so variants . . . without the rest of the model number, the specific parts list cannot be found.

Click to expand...

Here's what I've found:

71821C

6TPXS.1951AB 195cc

The tiller itself is 21A-663E766.

The engine is this one (minus the electric starter).



At this point, I've ordered a new coil and will be trying to get the gas tank off, which locks nearly everything else up in place. So far, no luck. Can't get started until I figure how how to pull this mysterious piece.

One thing, these coils have a pretty sensitive switching circuit and testing with a ohm meter can damage the semiconductor in there. Also, did you try another spark plug?

tom3 said:

One thing, these coils have a pretty sensitive switching circuit and testing with a ohm meter can damage the semiconductor in there. Also, did you try another spark plug?

Click to expand...

I never got that far. I just ordered a new coil. Low-mileage plug looks perfect and I couldn't produce arcing to ground in any case.

Eventually, I'll figure out how to remove the housing and actually get to it, hopefully by the time the new coil gets here. This is the worst one I've ever seen for sheer inaccessibility. Apparently, these are not intended to ever be serviced.

This is a 99% sure bet that it's the coil. It's been a first-pull starter since new, and I'd been using it only the day before. Turned it off and the next day it was stone dead -- not even a wheeze. Had the identical scenario with an old blade trimmer a year or so back. Bad coil. Replaced it (with a more modern version) and it was back to first-pull operation again. Nothing intermittent about a bad coil!

From what I can see (admittedly not much), the kill circuit is working properly and not shorted.

Thanks!

You have checked the kill wire/harness first, right? That is a far more common cause of a no start condition . . .

tom3 said:

One thing, these coils have a pretty sensitive switching circuit and testing with a ohm meter can damage the semiconductor in there. Also, did you try another spark plug?

Click to expand...

In a word, bull! A decent ohm meter eill *NOT* bother any semiconductor, and are often used to test them. They just don't output enough voltage or current . . .

tadawson said:

You have checked the kill wire/harness first, right?

Click to expand...

I can only see about a inch of the wire, where it disappears into the housing (that I still can't figure out how to get off). The kill mechanism itself seems to work fine. The ground wire appears to be fused to that by a permanent solderless connection, which I am reluctant to cut when I can't actually get to it. If it were just a matter of disconnecting a readily accessible spade fitting, I'd certainly try it.

In any case, I'm going to have to get the housing off to inspect either the coil or the ground wire.

I'm still betting a nickle on a bad coil. :smile:

[Later:] I finally managed to get the gas tank off! Later, when it cools down (88° at the moment!) I'll get the shroud off.

Got it off...easy once the tank's removed.

Bad coil, new one arrives Tuesday.

Thanks, everyone!

OK, here's the latest:

Got the new coil, installed it with ~.025" clearance at the magnet, put it back together -- still no spark!

Nothing, not even to ground!

How can this even be?

I read of this same misfortune with someone else's engine, but didn't see how it resolved...if it did.

Are those wrong clearances for this model?

Did I lose my mind and install it backwards? [Spark plug cable faces outward toward the pull starter]

Is it possible to test the coil?

Try taking a 3" x 5" card which is roughly .008" thick, doubling it .016" and reset the coil closer to the flywheel.

I have heard of flywheel magnet loosing their magnetism, does it pull a screwdriver close to it?

Other than it having points and condensor, it's possible the new coil is bad too.

Even though the spark plug is relatively new, try another one.

Regards

Jeff

jp1961 said:

Try taking a 3" x 5" card which is roughly .008" thick, doubling it .016" and reset the coil closer to the flywheel.

I have heard of flywheel magnet loosing their magnetism, does it pull a screwdriver close to it?

Click to expand...

Magnet certainly seems strong enough.

I've got a piece of card here that's .017" by micrometer. I may try something thinner. The tolerances were supposedly from .012" to .035"

Other than it having points and condensor

Click to expand...

No, none of those. This is supposed to be simple. :laughing:

it's possible the new coil is bad too.

Click to expand...

That sounds like my luck!

Even though the spark plug is relatively new, try another one.

Click to expand...

If I can, I'm simply going to eliminate it from the equation by using an ignition spark tester to ground. Of course, I have at least two of these but am having a time finding either of them.

Thanks!

You've already checked the grounding wire, they sometimes abrade away their plastic coating causing a short to ground. These are the only things I can think of.

I know the feeling of having 6 of one tool and not being able to find any.

Take a breather,,,,find your Zen, you'll get this ( I find either hot tea helps or lots of alcohol,,,LOL).

Jeff

Man, what a nightmare!

Latest: I ordered a different coil from a different seller. Got it today and put it in, gapped it, buttoned it up and NO SPARK AGAIN!

This is SUPPOSED to be the correct coil, superseding the old one. Fits perfectly...but it doesn't look the same and I wonder what's up. The odds against two different coils from two different manufacturers being dead out of the box seems astronomical.

Here are the three culprits:

https://i.imgur.com/YFsZABs.jpg

Here's the old coil:

https://i.imgur.com/QgAZtol.jpg

Thoughts?

Clearly it isn't the coil . . .

Have you ever put an ohmmeter to the kill lead as I suggested before you started throwing parts at it to verify that it is switching properly? This still screams that to me . . .

tadawson said:

Have you ever put an ohmmeter to the kill lead as I suggested before you started throwing parts at it to verify that it is switching properly? This still screams that to me . . .

Click to expand...

I did better than that. I totally removed the kill lead from the circuit. Completely. It can't be a factor.

I'm becoming convinced that in fact the original is substantially different from these later replacements. Look at the picture. It has a larger coil, bigger frame, larger resin body. It's a drop-in fit...but these replacements simply don't work. Never mind Chinese manufacture.

I'm getting about done with this experiment. I'm going to put a closer gap on tomorrow, and if that doesn't work, I'm off to the local mower shop to drop $43 + tax for their idea of a proper coil. It may turn out that these updated coils are erroneous.

[Later:] It lives! Big blue spark.

How I got to this point is a very interesting and edifying tale, which I'll get to tomorrow.

I also think I found the fault in the original coil.

Photos follow.

Observe!

OK, the replacement coil was good from the start, though my frame of mind wasn't. I was tired and discouraged, and I pulled the starter cord only twice in bright sunlight. The arc was out of my field of vision, and I was still wearing hearing protectors -- so I never saw nor heard anything relevant. Disgusted and assuming more bad luck, I just went in the house.

HOWEVER...I went back out at around ten PM (minus my hearing protectors) and gave it a pull and I saw a huge blue spark.

So, victory on the first real try. It starts on the first pull, goes fine.

So what was wrong with the first coil?

Here, look at this:



Note that the coil wire or some other component is soldered to the metal strap.

But look at it from another angle:



The metal strap was never properly prepped nor fluxed and the wire simply separated by about .003" leaving a stone dead coil.

Yes, I am going to demand a refund!

Golodkin said:

Yes, I am going to demand a refund!

Click to expand...

...and got it.

i am late to this party. Glad it is running again. When in a forum and asking for help I always put my city and state in just in case someone might be a neighbor who knows the device in question.

Super job and sticking with it.

near Cincinnati Ohio here/ ,, I seem to have the same issue on the same model engine I think this is mine hh60 105106f ser.9088c mine ran pretty good but at full throttle it just sounded like the engine was floating for lack of a better word, so only thing I did was change and set points, from that point on NO SPARK, even had a shop look at it, my question is , where can I locate procedure on how to set the gap for the coil to magneto ?

Setting the air gap is fairly easy, loosen the coil mounting bolts, get a index card and place in between the coil and flywheel, press the coil against the index card and tighten the 2 screws back up.