Johnson TD20 No spark at plugs...

[Barfass79]

Ok, So I have 3 Johnson TD20's. I just acquired a newer style than the older ones I have in which this one has a reverse switch on the side of the rewind. My main problem is spark at the spark plugs. This latest one I have tested the condensers (capacitors) and they are fine and I got brand new coils installed. Using my tester light I get great current at the spark plug cap but as soon as I plug a spark plug into it, there is no spark at the plug. I am VERY frustrated at this point as this is the way all 3 of the Johnson's have ended up... all good with the tester light but not spark plug sparky! Any ideas? I have cleaned the points and this newest one has new points installed, gapped correctly, etc...

At my wits end!!

 

[Barfass79]

Re: Johnson TD20 No spark at plugs...

Ok, So I have 3 Johnson TD20's. I just acquired a newer style than the older ones I have in which this one has a reverse switch on the side of the rewind. My main problem is spark at the spark plugs. This latest one I have tested the condensers (capacitors) and they are fine and I got brand new coils installed. Using my tester light I get great current at the spark plug cap but as soon as I plug a spark plug into it, there is no spark at the plug. I am VERY frustrated at this point as this is the way all 3 of the Johnson's have ended up... all good with the tester light but not spark plug sparky! Any ideas? I have cleaned the points and this newest one has new points installed, gapped correctly, etc...

At my wits end!!

An addition to my last post, the newest one that I just replaced the coils and points on is a TD-28 model Johnson.

 

[nwcove]

Re: Johnson TD20 No spark at plugs...

what type of tester light are you using to test for spark at the plug boot? sounds like you need to carefully go back over your work, and maybe post pics of what things look like under the flywheel(s)

 

[HighTrim]

Re: Johnson TD20 No spark at plugs...

Ill assume you have tried substitute plugs?

Will the spark jump a 1/4" gap on an inline adjustable tester? If not there are problems with the igniton.

The following may help.

http://www.pochefamily.org/outboard/Coils.htm

 

[seahorse5]

Re: Johnson TD20 No spark at plugs...

Don't forget that back in those days you also had to recharge the flywheel magnets. Not enough magnetism, then no spark or maybe a weak yellow spark.

Any chance of finding an old time mechanic with one of those Stevens flywheel magnet rechargers? Maybe you can find someone on the www.aomci.org site.

I'm assuming that you have the points cleaned and check out the wire continuity, coil resistance, and the condensers.

 

[Barfass79]

Re: Johnson TD20 No spark at plugs...

what type of tester light are you using to test for spark at the plug boot? sounds like you need to carefully go back over your work, and maybe post pics of what things look like under the flywheel(s)

I am just using a basic AC/DC test pen. I used this thing for years on outboards and many a motorcycle, but just for basic testing, if it lights up there should be something there, if it doesn't, then I know where to go next. I have never had this symptom before. I did go back through everything and re-checked the gaps and tested the coils, condensers and points as per the Poche family website... still no spark at the plug. Everything is new so was put in dry, I ran a business card through the points a couple of times to make sure no oil or sweat had got on them. Doesn't make any sense....

I will get some pictures soon. I am going to tackle changing the spark plug wires and caps next. Hopefully later on tonight once the little one is tucked in!

 

[nwcove]

Re: Johnson TD20 No spark at plugs...

not sure on the test light, as you can get voltage to the plugs, but not near enough to make a plug spark. just a thought, but an open air spark test tool is cheap, or you can make one quite easily. if the wires are original, that could easily be the issue.

 

[steelespike]

Re: Johnson TD20 No spark at plugs...

As I recall That uses a Magnet rotor be sure the magnets are strong and it is installed right.
Be sure the point push rods are operating freely and points set the same.
If the push rods are dragging they will not let the points close in time also be sure the points are indeed closing.
Check the air gap between coils and magnets.Your business card should do for that.

 

[Barfass79]

Re: Johnson TD20 No spark at plugs...

not sure on the test light, as you can get voltage to the plugs, but not near enough to make a plug spark. just a thought, but an open air spark test tool is cheap, or you can make one quite easily. if the wires are original, that could easily be the issue.

This is definitely my next step. Everything else is new and the wires look original, so those are on the list. No time tonight to change them out, hopefully tomorrow.

 

[Barfass79]

Re: Johnson TD20 No spark at plugs...

As I recall That uses a Magnet rotor be sure the magnets are strong and it is installed right.
Be sure the point push rods are operating freely and points set the same.
If the push rods are dragging they will not let the points close in time also be sure the points are indeed closing.
Check the air gap between coils and magnets.Your business card should do for that.

This model is a TN-28 with the neutral switch on it. (thought this was reverse.. hahaha!) My other 2 are TD-20's and are like you describe. The TN-28 thankfully has the more modern points. I will however check the old TD-20's push rods and see if they need a cleaning. That was not something that I really checked. Thanks!

 

[HighTrim]

Re: Johnson TD20 No spark at plugs...

Ah the ignition on the TN28 is much different than the older TD20 as you know, it has the newer universal ignition.

I would get an inline tester, set it to 1/4" and see if there is spark. Use the recoil, sometimes just spinnig the flywheel by hand wont cut it.

If not, ensure the points are gapped properly, and are CLEAN, even a fingerprint will hinder spark. Test the wires for continuity. Ensure the wire was twisted into the coil pin. Ensure that the spring clip has properly punctured through the center of the plug wire under the boot. I like to cut off a bit of the insulation and fold the copper strands back over the wire to make better contact with the spring.

 

[sutterhome]

Re: Johnson TD20 No spark at plugs...

Question on td 20.Got my hands on on of these to play with.No spark at either plug.Before I get crazy with it, is the stop function a kill switch or does it just retard the spark till it dies. I'm referring to the throttle control level stop, start and fast.
All electrical components coils, points wires look solid.But I figured I would start at the obvious 1st.

 

[F_R]

Re: Johnson TD20 No spark at plugs...

You're reopening a year old thread.

Retarding the lever all the way toward stop closes the kill switch. 90% of the no-spark problems on those old rotor style magnetos is due to dirty points. There is only one good way to clean them...Take them apart and polish each contact shiny-bright, then reassemble & reinstall & set gap to .020" at widest opening. Do one set at a time so you have a sample of how they go back together, and don't lose any of the many small insulators.

Now, let's put this thread back to bed for reference only.