Tecumseh ignition

Royse · Jan 17, 2021

I'm trying to resurrect this old Tecumseh engine and getting no spark.
I replaced the points and gapped to .020.
My meter shows me they are opening and closing electrically.
I also replaced the coil after this picture was taken.
The condensor is not shorted so it is not grounding anything out.
The engine rolls over at normal speed using the starter.
I'm not sure how to set the air gap on this setup, but what else
could I have missed? The whole mower mower sat outside for
about 10 years without being ran so it needs some work.
It's a Simplicity Broadmoor.

old · Jan 17, 2021

Flywheel magnet weak or flywheel real rusty can cause that. As for coil gap a business card between the flywheel and he coil is about right

John T · Jan 17, 2021

I don't have any coil gap settings, if adjustable I set them as close as possible without making contact and clean/polish the
flywheel magnets. If there is any kill switch wiring I have seen them get shorted out.

John T

old · Jan 17, 2021

Last time I got a new coil for an engine like that is came with a plastic gauge that was about as thick as a business card. The turned the flywheel so the magnet was in line with the coil and put the plastic gauge between the 2 and tighten down the screw that hold the coil. Then you turn the flywheel while pulling on the plastic gauge and you have it set as it should be

wore out · Jan 17, 2021

(quoted from post at 10:46:40 01/17/21) I'm trying to resurrect this old Tecumseh engine and getting no spark.
I replaced the points and gapped to .020.
My meter shows me they are opening and closing electrically.
I also replaced the coil after this picture was taken.
The condensor is not shorted so it is not grounding anything out.
The engine rolls over at normal speed using the starter.
I'm not sure how to set the air gap on this setup, but what else
could I have missed? The whole mower mower sat outside for
about 10 years without being ran so it needs some work.
It's a Simplicity Broadmoor./quote]

The "air gap" is NOT adjustable, the slots the stator attaching bolts pass through allow the whole assembly to be rotated to set the spark timing, there's a procedure in the shop manual for that.

Try a new condenser, just because it isn't "shorted" doesn't mean it isn't "leaky" at the high spike voltages it "sees" in operation, or "open".

Richard G. · Jan 17, 2021

When I was a kid, we used penny postcards to set the air gap.
I think a post card was 10 cents then.

dzc3 · Jan 17, 2021

I used a business card to set the air gap seemed to work ok

Royse · Jan 17, 2021

I assumed the slots were for timing and I don't have a manual so
I just scribed marks on them before I took it off and then put it
back where it was.

If the timing were off a little, I could see it not running or not
running well but I should still get spark as some point. No?
I'm using an adjustable gap spark tester to check it.

I was wondering how you were supposed to set the air gap when
the coil sets inside the flywheel instead of on the outside of it.
It can't be reached once assembled. So I didn't see how to use
the normal gauges. It didn't make much sense to me.
Thanks for letting me know it's not adjustable.

sixbales · Jan 17, 2021

Capacitor shorted?

gab · Jan 17, 2021

No air gap to set, those two bolts in the slots are for setting the timing. It's done by pulling the head and positioning
the piston so many degrees BTDC with a feeler gauge and straight edge or a special tool through the spark plug hole and
dial indicator. If there's no evidence of the bolt heads being moved it's probably ok but I got the book with the specs if
you need it.

Royse · Jan 17, 2021

Here's a picture of the magnets on the inside of the flywheel.
The flywheel has some rust but the magnets look Ok I think.

wore out · Jan 17, 2021

Verify there's no short/leakage to ground between the common connection of the points, coil and condenser and replace the condenser.

If the coil has been replaced AND the points are clean and making contact it's the only part left to make a weak spark.

Gene in Mi · Jan 17, 2021

What John T said. Verify kill wire is not grounded. Can be checked at ignition switch. It might be a green wire connected to "M" terminal on switch.

Royse · Jan 17, 2021

I'll pick up a new condenser for it, they're not much money.
I think the coil and condenser may be originals.
They are both marked with Tecumseh and the part number and
they were connected together with the wires from each going
to opposite sides of this common connector.
The condenser wire is still hooked to the left side of it here.

gab · Jan 17, 2021

I got a free little wheel horse in about 1980. It would start but not easy and would start loosing power within about
20 minutes, I could turn out the power needle a hair and it would be normal for a few minutes and die. I tried
everything over and over and parked it in the shed for over 30 years.
Ran across another running Tecumseh 6 Horse at an auction a few years ago for 5 bucks and started swapping parts. When
I swapped the flywheel she came to life, starts instantly and runs like a new one.

After all that I rebuilt the whole thing a couple summers ago.

Royse · Jan 17, 2021

I sure hope it's not the flywheel. They're not cheap.
Know any accurate way to test the flywheel and magnets?

MtMan · Jan 17, 2021

I would clean the rust off the flywheel and check the magnets to see if they will grab and hold a screwdriver blade. Then you will
know if the fly wheel is okay. I might think that is your problem. Good Luck

wore out · Jan 17, 2021

"I think the coil and condenser may be originals. "

You said in your first post you had replaced the coil. Or did I read that wrong?

With the (strong/long lasting) ceramic magnets in good looking shape and still glued in place I think it's a million to one that the flywheel would be the issue.

What's the history, is it new to you or has it run for you in the past?

If you've never seen it run I suppose it COULD be something WEIRD like the wrong flywheel.

UncleTom · Jan 17, 2021

That has the charging coils as well as the ignition coil. The big one is the ignition coil. Do you have an analog meter? If so short across the condenser to ground it out. Then take your analog meter and set it on ohms scale, touch one lead to the capacitor and the other to the wire. The meter needle should bounce off of zero a small bit and then back if the condenser is good.

47fivewindow · Jan 17, 2021

I don't see any oil leakage so this is a long shot. Is the top main crank
bushing loose causing the point gap to change?

Royse · Jan 17, 2021

You did not read it wrong, I replaced the coil.
What I meant was the coil I took out and the condenser may be originals.
It has ran for me in the past but it has been about 10 years.
I don't use it to mow my yard, I was just going to get it running
again and use it to pull a dethatcher and lawn sweeper.

Royse · Jan 17, 2021

I don't feel any movement in the shaft other than rotational.

Royse · Jan 17, 2021

Yes, a screwdriver will stick to each of the six magnets.

Steve@Advance · Jan 17, 2021

Is the key tight in the crank and flywheel slot? Not partially sheared?

Try playing with the timing bolts, those are very sensitive to when the points open in relation to when the magnet just passed the coil.

You can also tweek the point gap closer or wider a few thousandths to change the opening time.

I know, it sounds crazy but nothing to loose by trying. Remember the old B&S that would shear the flywheel key, they would loose spark. Replace the key and spark would happen, same thing.

You could also order a points eliminator.
Points Eliminator

Royse · Jan 17, 2021

Thanks Steve, the key is fine. I've dropped it several times taking
that flywheel off and putting it back on. LOL

old · Jan 17, 2021

I've used those little modules many times over the years. I had an old tiller that ran fine as long as you didn't engage the belt but when you did it died. Found the problem to be the front of the engine was wore enough that engaging the belt would to make the point not open correctly. It also smoked badly and when you wanted to use it you check the gas and fill the oil

Royse · Jan 29, 2021

I wanted to follow up so you guys that tried to help me would
know what I found. Two bad coils. The old one and the new one.
A "known good" used one from a neighbor fixed it.

wore out · Jan 29, 2021

A SAD fact of life today is that the quality control dept. no longer exists and it's function has been transferred to the customer.

Was the "bad" new coil from "The Land of Almost Right", a genuine Tecumseh part, or a NOS Tecumseh part?

For ignition parts nowadays I first look on ebay for a good 'ol "Made in USA" NOS part.

Tecumseh ignition

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