No spark

[Nyquil Junkie]

(quoted from post at 11:57:49 07/07/23)

But many coils, especially ones that fail after a little operation have deep seated emotional issues. Your testing would either have to include some kind of temperature test, where you warm it up and see what happens

Deep seated emotional issues... I like that one.

A similar problem I had on my old toyota Pu. it would run fine then die when it got warm. Let it set a while and vroom it started back up. It drove me nuts for a year that way. I got 1001 suggestions why it did that none turned out to be right.

What it was is, the can coil had a hairline crack in it. when it warmed up, it dripped the oil out in such a position that you didnt really see any trace of it. Over time it lost more oil.. got worse. One afternoon I noticed oil down on the innter fender where oil shouldn't be....Then it hit me. The can coil is full of oil. I looked close and bingo, I see a tiny crack w oil traces.

That and the coil was HOT.

The kicker is, I replaced that can coil when it first started dying every now and then. Why think the newish one was bad too?

Well it was, probably had a defect in the case that cracked under vibration and heat.

The sq can in question here doesnt have oil IIRC but... same difference. it might be something you aint considering "possible".

A crack.. a defect...who knows. probably 1 in 10 parts I buy for various machines here have some problem right out of the box.

Ive never had a square can coil in my hands to examine but I bet there is some tiny thing going on here thats easy to remedy when you find it.

Might not even be the coil...might be some random thing along the line somewhere shorting out the system like the key switch or a dirty connection or... something.

 

[Caroline Chamblin]

Of course you're right JMOR, and sensible. It
would buy me some time to work on it without
the factor of overgrowing grass. I have even
considered a new tractor because financing is
so favorable. Illustrates the weaker side of
my personality. One of my faults, getting
stuck and looking for an easier ( at the time)
way out.

 

[Caroline Chamblin]

I have installed a new distributor prior to testing (this is the second round on testing)

Voltage at coil 6.41 volts
No change with engine turnover
1. New distributor washer looked good
2. 1.1 ohms
3. New distributor
4. Cleaned mating surfaces, new gasket
5. 7k ohms
6. New distributor
7. Tight bail coil appears secure
8. New distributor
9. New distributor
10. New distributor

 

[Bruce (VA)]

You points are grounded. You should see the voltage drop when the points close. Go back and run the 4 continuity checks again.
75 Tips

 

[Hobo,NC]

Whats gonna help ya get a grip on this is remove the dist. chuck it in a vice and wire it up with the coil off and laying beside it. This is one reason I hate a front mount but have enoufh common sense to wire it up for test like it was an external coil application.

All the dist is is a switch so instead of using the coil I use a light bulb. Once I get the dist to turn the bulb of/on I then assemble the coil and cap and make spark while its in my vice.

That's about as simple as i can make it and no need to write a damm book about every possible scenario to confuse you. Its not that hard and the issue will be right there in front of you.

 

[Caroline Chamblin]

I see your point Hobo. Light on light off and
so on. We used the meter for continuity test
per Bruce this time. Thank you.

 

[Caroline Chamblin]

Bench test of the 4 tests on distributor were all consistent with correct functional distributor.
1. Coil off, cap off, points open. One probe on the brass screw & the other on both sides of the open points. On the side closest to the cam, you should have continuity. Not on the other side! If you do, you will also have continuity everywhere because the points are grounded.


Cam side + for continuity
Other side No.

2. Coil off, cap off, points open. One probe on the brass screw & the other anywhere on the body of the distributor. You should have no continuity! Now, rotate the tang on the distributor....as the points open & close, you have continuity (closed) and lose it when they open.

As shaft turns and point open and close, continuity found and lost cyclically.



3. Put the coil on the distributor, cap off, points open. One probe on the lead on the top of the coil, the other on the cam side of the open points. You should have continuity!


We got continuity.


4. Coil on, cap off, points open. One probe on the lead on the top of the coil, the other anywhere on the body of the distributor. You should have no continuity!

We got no continuity.

Reinstalled and no change in tractor.

 

[Caroline Chamblin]

Here are photos of the set up I tested today. Test results in reply to Bruce near bottom of thread.
A new distributor, continuity tested and found ok on bench. No change tractor turns over no spark. See how bent the pigtail looks. It could be you H the ting?

 

[Hobo,NC]

(quoted from post at 08:30:59 07/12/23) I see your point Hobo. Light on light off and
so on. We used the meter for continuity test
per Bruce this time. Thank you.

Whats a coil, answer a load.

What does a load do in a circuit, answer it consumes the voltage in the circuit.

Can you confirm a circuit is good with a ohm meter, answer NO

Does a continuity test put a load a circuit, answer NO

Continuity does not load the circuit nor does it confirm the circuit's health. This is old school testing ohm this ohm that it confirms nutt'in its a hope and a payer at best.

If you put your faith in a continuity test sometimes it will eat your lunch. Facts are facts and this is one of those times back your test with a known good load.

The time has come to supply a know good load a load you can see work.
The time has come for those continuity test lubbers to step up their game.
It has continuity is not the right answer "Prove it" : )

Prove it is your map to success.

This post was edited by Hobo,NC on 07/12/2023 at 04:30 am.

 

[lastcowboy32]

(quoted from post at 04:24:32 07/12/23)

(quoted from post at 08:30:59 07/12/23) I see your point Hobo. Light on light off and
so on. We used the meter for continuity test
per Bruce this time. Thank you.

Whats a coil, answer a load.

What does a load do in a circuit, answer it consumes the voltage in the circuit.

Can you confirm a circuit is good with a ohm meter, answer NO

Does a continuity test put a load a circuit, answer NO

Continuity does not load the circuit nor does it confirm the circuit's health. This is old school testing ohm this ohm that it confirms nutt'in its a hope and a payer at best.

If you put your faith in a continuity test sometimes it will eat your lunch. Facts are facts and this is one of those times back your test with a known good load.

The time has come to supply a know good load a load you can see work.
The time has come for those continuity test lubbers to step up their game.
It has continuity is not the right answer "Prove it" : )

Prove it is your map to success.

This post was edited by Hobo,NC on 07/12/2023 at 04:30 am.

Check this tab on the coil. Make sure it is well sprung. I installed a new coil on my tractor a few years back, and I had no spark at all.

I removed the distributor cap, clipped a my spark tester lead directly to this tab... and it had spark.

So, my only deduction was that this tab was not making contact with the cap... or the rotor was not making contact with the cap.

I bent this tab out a little more to get some better spring to it... and tractor roared to life.

 

[lastcowboy32]

Was a PITA on the tractor. If you are bench testing... seems as though this would be easier to do on the bench, if you had a spark tester and a few alligator clip leads.

Just... please keep your hands off the spark test leads when you rotate the distributor and open/close the points. If your coil is good, you'll get an unpleasant surprise.

I was about 12 years old, riding an old Honda 110 ATC when I learned about spark voltage... every time I rode through a mud puddle, it would skip and sputter, because the front wheel would throw water/mud on the spark plug boot/wire.

It happened one time, and I figured I would just reach down with my left hand to wipe the mud off... that was a mistake.

 

[lastcowboy32]

If you DO get spark at the tab.

Put your distributor cap on and sequentially test all four ports on the cap with your spark tester.

If you get spark at all four ports... a nice blue spark that jumps a quarter inch gap... then your ignition system is working to that point.

Then it would be spark plug wires, spark plugs, fuel or timing left to check, if it still aint runnin'

 

[lastcowboy32]

I would also go so far as to say... it's not a good idea to energize a coil and close/open the points without some kind of spark gap attached to that tab.

The coil is essentially a transformer that builds up flux when the primary is energized (points closed)... that flux will then increase the voltage on primary and secondary when the points open... to whatever voltage is necessary to collapse that flux.

The spark gap usually provides the relief valve (hence spark plugs work)... without that spark gap? All bets are off. The voltage will rise and an arc will jump somewhere possibly internally to the coil, and you won't like the consequences.

 

[Caroline Chamblin]

So run the test with your light bulb method?
That's what you mean Hobo? The reinstallation
on the tractor and trying to start doesn't
test since it could be downstream from the
coil/distributor set up? Remember it just died
out in the field , thank.you . like turning
off the key.

 

[lastcowboy32]

We (including myself) write to learn about ourselves... so this comment is a critique of my own comments.

I have a logical gap in my understanding of your problem.

Tractor shuts off in the middle of the field after running for some time.

BIG LOGICAL GAP

Troubleshooting coils, distributors, etc, etc, etc.


Within that logical gap would be all of the failures that could lead to no voltage at the top of the coil...

Ignition switch failure

Ignition wiring failure

Ballast resistor (if there is one) failure

Loose terminal in the path from generator/battery to ignition circuit.


And... all of these things could be intermittent... leading to a tractor that runs for a while and stalls out, maybe after it gets hot... or hits a bump just right in the field.


Hobo has seen it all... so you're in good hands.

My comment is mostly defensive... because... anybody could read my comments and say... the coil can only produce spark if it has power in the first place...

And...from reading your post and all comments after? I'm still not sure that it does have power, on the tractor, at the moment that it fails.

 

[Caroline Chamblin]

Hi Hobo
I did this test and got spark at the coil on
the bench. https://youtu.be/fD6KLx8B_UE

 

[Caroline Chamblin]

Thanks lastcowboy32
I understand how you feel reading all of the
information. Believe me I'm tired of this. I
almost bought a brand new tractor! I just
don't want payments because that's risky
sometimes. But it may come to that. And this
is not a complex system. I have battery
voltage at the coil when ignition turned on
but it doesn't drop to half when turning
engine over. The bench testing of coil and
distributor results shown, and then tested
coil using the following video.
https://youtu.be/fD6KLx8B_UE

 

[soaked]

Hi CC, is the old abandoned remote round can coil still used as a terminal in the square coil ignition curcuit? If so, im suspicious of the patched up wiring.

Could rig a spark tester, and bypass with jumper wire.

John in lake stevens

 

[Caroline Chamblin]

Hi John
I have removed it and rewired according to JMOR diagram for 6 volt system.

 

[soaked]

Is your camshaft turning the distributor?
If its broken, or its pressed on fiber gear fails, the dist wont turn.
Hope its just a wire issue.