Toro self propelled lawn mower ignition problem

[klem kedidelhopper]

Someone gave us this non working self propelled mower that he says
just stopped working. When my son first tried to start it he says that
it would run for a few seconds and then quit. After this it would
apparently take about 20 minutes before it would again start, and
again run for about two seconds and then the process was repeated.
This morning we worked on it a little and I could not get it started
at all. We ultimately found that there was no spark. I don't know what
happened when he worked on it. The ignition kill switch is working,
There is no short on that terminal in "run" position, the rust has
been cleaned off both the rotor and stator areas of the flywheel and
transformer and the plug of course looks OK too. There are no points
or capacitor on this mower and there is just a magnet on the
flywheel.The coil has a secondary wire to the plug, a terminal that is
grounded to the transformer laminations with a self taping screw, and
a terminal connected to the kill switch. Unless I'm missing something
the operation of this system seems pretty cut and dried without
timing or anything else being an issue, that as the magnet passes by
the coil a voltage should be induced into the secondary. Am I correct
in this assumption? Is there a way the positively bench test this coil
before we go out a buy a new one that will no doubt be non returnable
if it's not needed? Thanks, Lenny

 

[[email protected]]

Someone gave us this non working self propelled mower that he says
just stopped working. When my son first tried to start it he says that
it would run for a few seconds and then quit. After this it would
apparently take about 20 minutes before it would again start, and
again run for about two seconds and then the process was repeated.
This morning we worked on it a little and I could not get it started
at all. We ultimately found that there was no spark. I don't know what
happened when he worked on it. The ignition kill switch is working,
There is no short on that terminal in "run" position, the rust has
been cleaned off both the rotor and stator areas of the flywheel and
transformer and the plug of course looks OK too. There are no points
or capacitor on this mower and there is just a magnet on the
flywheel.The coil has a secondary wire to the plug, a terminal that is
grounded to the transformer laminations with a self taping screw, and
a terminal connected to the kill switch. Unless I'm missing something
the operation of this system seems pretty cut and dried without
timing or anything else being an issue, that as the magnet passes by
the coil a voltage should be induced into the secondary. Am I correct
in this assumption? Is there a way the positively bench test this coil
before we go out a buy a new one that will no doubt be non returnable
if it's not needed? Thanks, Lenny

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

 

[klem kedidelhopper]

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 :-#)#

--
    (Please post followups or tech enquiries to the newsgroup)
  John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
  Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
                     www.flippers.com
       "Old pinballers never die, they just flip out."

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

 

[Bob Engelhardt]

...
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

 

[klem kedidelhopper]

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

 

[[email protected]]

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

Yes. Look here:
http://home.howstuffworks.com/home-improvement/repair/how-to-repair-small-engines3.htm

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

 

[Bob Engelhardt]

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

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

 

[klem kedidelhopper]

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

 

[klem kedidelhopper]

Ask and ye shall receive:
<http://www.jackssmallengines.com/toro_model_locator.cfm>

--
Jeff Liebermann     [email protected]
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

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

 

[klem kedidelhopper]

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:
<http://www.ereplacementparts.com/toro-20016-2600000012609999992006-la...>
Looking at the engine diagram, there are no points or condenser.  Ok
so I was wrong.  Ignition coil:
<http://www.ereplacementparts.com/ignitionstate-solid-p-685744.html>
Oh swell... it's a special order.  Digging for other vendors that
carry a 34443D.
<http://www.ebay.com/sch/i.html?_nkw=34443d+coil>
$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.

--
Jeff Liebermann     [email protected]
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060http://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

 

[Bob Engelhardt]

... 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. ...

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

 

[William Sommerwerck]

... you should never fire an ignition coil with the secondary

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

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

 

[Bob Engelhardt]

When the coil creates a high voltage, there will be an arc wherever
the gap is the smallest. ... it could arc inside the coil and thereby
destroying some high voltage insulation. ...

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

 

[bw]

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

Bob

Yes. Many. Thats how they fail. Temperature, vibration, aging induce small
cracks in the insulation. Dirt, moisture infiltrate, etc. Better coils are
designed with internal aux gaps greater than the normal spark plug gap. I've
dissected failed coils, not hard to find traces of internal arcing, melting.