Toro self propelled lawn mower ignition problem

It's been a long time since I worked on lawn mower engines, but every one I ever saw had points and a capacitor. On vertical shaft engines they were typically under a cover under the flywheel. Now I will admit that this experience was well before the wide spread use of solid state devices, but there MUST be some method of interupting the primary circuit as the crankshaft nears top dead center. Also, the presence of a capacitor is pretty well mandatory.

PlainBill

Have you downloaded the manual from Toro.com? May have a troubleshooting guide...

Otherwise regular small engine repair books should be enough to get through the lack of spark problem.

John :-#)#

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These appear to be owners manuals. How to change the oil, etc. There really isn't anything mentioned that goes into anything that technical like bench testing a coil. I really think it is the coil. I just don't want to order one, about 20.00 and then possibly be stuck with it. Anyone have any ideas? Thanks, Lenny

I just went through this. I didn't want to believe that the coil was bad (a new one was $40). But there isn't a way, that I know of, to bench test. If you don't have a spark, it's bad.

To test:

- remove the kill wire

- remove the spark plug, attach the coil wire, & ground the plug

- pull the cord & watch for a spark on the plug

This is better than trying to get a spark between the coil wire & ground.

Bob

Wow, 40.00 for a coil! I am probably facing the same thing. I hope you at least got a kiss out of it...Lenny

Yes. Look here:

The pictorial diagram and the two pictures match what I remember from

50 years ago. I also see references to solid state ignition systems used on these engines, that came well after the time I worked on them.

If you can pull the coil without finding any wires other than to the kill switch and to the spark plug, the problem must be either the coil, the magnet in the flywheel, the spark plug, or the spark plug wire. The spark plug would seem to be the only replaceable part other than the coil.

PlainBill

Model number of the Toro mower?

How many seconds is a few? If it's about 2-4 seconds, then you've got spark and some fuel. My guess(tm) is that you have a clogged fuel filter at the end of a hose banging around in the fuel tank. Fish out the fuel filter and hose with a coat hanger and replace the filter. No, don't try to clean it... just replace it. There may also be a filter at the fuel entry hose to the carb.

Yep. It takes that long for fuel to sloooooooowly ooooooze through the clogged fuel filter.

Sigh. One giant step backwards.

Remove spark plug. Reconnect wire from ignition coil. Ground the plug some place convenient on the engine (not the gas tank). Crank. Do you see sparks? If not, check the points.

Keep looking. The breaker points and condenser might be buried.

Perhaps if you supplied the model number, an exploded view might be found?

How to test a magneto:

Shopping and todo list:

1. Fuel filter
2. Points and condenser.
3. Replace fuel line hoses if they're plugged or cracking.
4. Spark plug.
5. Clean out engine exhaust port from carbon buildup.
6. Clean out engine intake port from tar buildup.
7. Carb cleaner.
8. Check the magneto gap.

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Jeff Liebermann     jeffl@cruzio.com
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...

Lawnmowers haven't had points for 20 (30?, 40?) years.

True. I hate it when I date myself. I haven't had a lawn for about

35 years. We don't have lawns in the deep dark forest. Most of my small engine repairs are on chain saws and weed whackers, many of which have points and condensers.

If it's an old riding mower, it has points and condenser on the engine. If it's newer, it's an electronic ignition. I'll wait for the model number to be disclosed to be certain.

My comments on the fuel system problems still apply.

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Skype: JeffLiebermann     AE6KS    831-336-2558

Greetings Lenny, The electronics in the coil are probably bad. If you try the test suggested further down this thread and there is still no spark then it is very likely the electronics are bad. I have seen some coils that have the trigger electronics located in a bump on the coil. These types can sometimes be removed and replaced with aftermarket electronic ignition modules. It has been a long time since I've done this so maybe this won't work for you. The magneto works like this: the primary is grounded and the magnet passes quickly past the legs of the magneto assembly. At the proper moment the ground is disconnected and the collapsing field induces a voltage in the secondary. The aftermarket electronic ignitions sense the rising voltage and open the ground connection at the proper moment. So if you can get to the electronics and remove the connections, then figure out which wires are which, you can then maybe use an aftermarket module to make the thing work. Briggs and Stratton used to make an electronic ignition that worked differently than described above. It had some sort of coil that sensed the flywheeel position(Ithink). I never tried to hack one of those, just replaced parts. But I have repaired a few of the types described above. I have even just wired in an aftermarket electronic ignition on a weed trimmer that lost spark. The ignition module was made for a Tecumseh engine but since I had it already I just wired it the way I would have if I was retrofitting a points type ignition. The weed trimmer unit had obviously failed with the ground permanently connected and since the new module opens the ground to get spark it worked fine. If you don't mind a shock you can try what I do. I grab the spark plug wire and pull slowly on the starting rope. If I don't get even a tingle then I pull faster. If I get a good shock then that means either a bad spark plug or bad connections. If I just get a pretty good tingle then that probably means that the coil is being permanently grounded and I'm feeling the rising field. This is hopeful because it means that maybe an aftermarket ignition module will work since they just interrupt the ground. Whew! I didn't think this reply would be so long. Eric

Wow Eric thanks for the theory. I think that it is a good bet that the electronics in the coil has failed. I'm pretty sure that I can get a used coil from a lawnmower repair guy in this area. There are a number of people that work on these and sell used mowers. I'm thinking that they must keep used parts around. I wish I could find the model number of this thing. Lenny

Ask and ye shall receive:

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How do you find this shit Jeff? It's a model 20016. Lenny

I usually use a crystal ball. However, it's in the shop getting its temporal dimensional translator recalibrated. So, I had to settle for Google. A search for "Toro find serial number" immediately yielded the correct site on the first page (at the bottom).

Here's the exploded view of the 20016:

Looking at the engine diagram, there are no points or condenser. Ok so I was wrong. Ignition coil:

Oh swell... it's a special order. Digging for other vendors that carry a 34443D.

$25.

However, I'm still suspicious that it's a fuel problem based on the original symptoms. I'm not sure why it now doesn't have a spark. Performing at least one of several recommended test should help eliminate lack of spark as a probable cause.

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Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

I have eliminated an internally arcing spark plug as a possibility because I tried sticking a screw driver into the boot and acing it to ground and there was no spark with that method. In addition, with the shroud (with the starter pull rope) removed, and turning the engine with a drill the high voltage wire is well removed from chassis ground so it arcing is not the problem either. However now I think that I know what may have happened. I ran across the sites below that had really good writeups on small engine ignition theory. The second one happened to mention that you should never fire an ignition coil with the secondary disconnected from the spark plug or as they put it a "suitable load". The article went on to say that doing so could cause internal acing in the coil and damage it. I never knew this but it makes sense and incidentally adds up as well. I happened to mention this to my son this morning and he admitted that during the course of his working on the engine when he had it running for a few seconds and then it would die he had done this very thing. And mysteriously now we have no spark where he did before. So a new coil is about twenty five dollars and I'm thinking that should hopefully take us back to square one where we should be back to the two second run problem, (I hope). If I knew that it was just the coil I guess I'd spring for the twenty five bucks plus freight. However given the history with this engine I'd rather not go throwing a lot of money at something that may need a carburetor or more as well. I gotta go see the used lawn mower guys this week and hopefully find a coil. Lenny

Although that sounds plausible, I'm skeptical. First, I don't see how an internal spark would happen. I.e., what the path would be. But even if it could, I've fired disconnected coils lots of times without problems.

An alternative explanation would be that the coil was marginal at the start - good enough to run for the few seconds. Then failed altogether. I don't know if there is a coil failure mode like that, but I wouldn't rule it out.

Bob

And how is external arcing "somewhere else" different from arcing across the spark plug's gap?

When the coil creates a high voltage, there will be an arc wherever the gap is the smallest. That is supposed to be the spark plug. If the plug isn't there, it could arc inside the coil and thereby destroying some high voltage insulation. It is possible that from then on, the shortest gap is inside the coil. I am not saying that is what happened - just explaining what the warning meant.

You're right, but there are limitations. First, the voltage isn't unlimited, it has some maximum, whether there's a gap or not. I don't know the mechanisms limiting it - parasitic capacitance, leakage current, I dunno. Hopefully the coil designer knew and insulated against it, maybe.

Then there's the path of an internal arc. There's certainly not enough voltage for an arc between adjacent turns. Also very unlikely between adjacent layers. The highest voltage is between the last turn and the core. But that's the most heavily insulated path.

I'd be convinced by an actual case of an internal arc - anybody ever see one?

Bob