No Spark to Tecumseh Tiller Engine!

Golodkin

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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:

Ignition_Coil_Tec_34443A__88834.1439187356.1280.1280.jpg

I have most electronic testing devices.

Thanks for any advice.
 

tadawson

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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:

View attachment 43650

I have most electronic testing devices.

Thanks for any advice.

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).
 
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Golodkin

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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).

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? :confused:

If no, what is that #315 thing?

Tiller.PNG

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!
 

tadawson

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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.
 

Golodkin

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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.

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).

engine.PNG

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.
 

tom3

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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?
 

Golodkin

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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?

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!
 

tadawson

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

tadawson

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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?


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 . . .
 

Golodkin

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

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.
 
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