212-H NO SPARK WHEN ENGINE HOT

[Calvin Jones 4]

Mower ID # 32-120E01, 11812 0075 with a Toro Power Plus ONAN engine (E125V-N/10964B S/N A903645964).  I'm not that familiar with this engine or mower. 

 

When cold the engine starts right up and continues to run normally until it is shut off.  It will not start back up until it cools down (~30 minutes).  There is fuel, but no spark when it will not start. The coil resistance readings are in the acceptable range when engine is cold.  I suspect the coil windings are breaking down as it heats up.  I have not tested the coil when heated.  I did pull the two grounds I found and made sure they were cleaned and tight.  I also replaced the spark plug.  I have not tested the ignition module under the fly wheel.  My plan was just to purchase a new coil because I suspected it would be around $30.  My research found the coil needed is a Toro NN10730 ONAN # 0166-0799.  Every source I found for this coil wanted nearly $300.  Way more than what I want to pay for a small engine coil.

 

I'm planning to pull the coil when heated up to see if the resistance is still within specs. Any other suggestions?  Are there any other components I should check?  Is there a specified gap for this coil?  Is there a substitute coil that will work at a more affordable price?  Thanks in advance for any assistance.

[gwest_ca-(File Mod) 10,539]

To verify it is not the tractor wiring causing the shutdown you need to disconnect the dark blue wire going to the magneto as close to the engine as possible.

 

[lynnmor 6,850]

1 hour ago, Calvin Jones said:

Mower ID # 32-120E01, 11812 0075 with a Toro Power Plus ONAN engine (E125V-N/10964B S/N A903645964)  I have not tested the ignition module under the fly wheel.

 

My guess is that the module became heat sensitive.  Do your hot coil test before spending money on a module, just be ready to immediately test the coil upon shutdown.  Are you sure that there is a module under the flywheel?  Can you post a photo of the coil?

Edited July 14, 2022 by lynnmor

[roadapples 6,981]

[Calvin Jones 4]

I would like to start this update by thanking, "The Wheelhorse Master" and the, "Wheelhorse Pro" for your prompt response and willingness to help this newby to the forum.  Also, thanks to Roadapples (RedSquare Expert) for the warm welcome.  The documents provided by Wheelhorse Master have been very helpful in my troubleshooting efforts.  Also, I need to clarify my misunderstanding of this ONAN engine.  I looked at the Master Parts Viewer incorrectly. The voltage regulator is beside the flywheel, not under.  Pics of the voltage regulator and coil module are attached.  I know the numbers aren't very clear in the pic.  The first one is, "BN35" or "BN85".  I can't distinguish between the 8 and 5.  The other number is 709G. 

 

I disconnected the dark blue wire going to the coil as suggested.  Engine started fine when cold, but would not shut off by turning the key.  I had to pull the plug wire.  I believe that is normal because that's part off the kill circuit, right?

 

I tested the voltage regulator using test 1 and 2 if the Troubleshooting guide.  Test 1 with engine off battery reads 12.82 vdc. Test 2 with engine running the voltage is 14.05 vdc.  I ran test 2 when the engine was cold and again when hot. Voltage just climbed to 14.06.  Both test 1 and 2 results are in specification so it appears the regulator is ok.   

 

Coil test results this time were different than I initially reported.  With coil cold the primary resistance (1P to coil core) read 2.0 Ohm.  The spec is 1.0 according to provided TS guide. When hot the primary resistance increased to 3 Ohm.  Now the strange thing.....the secondary resistance should be 9.5K Ohm from spark plug cable to coil core.  Both with coil cold or hot the secondary resistance was max (an open).  I must be doing something wrong or my meter was reading incorrectly.  That can't be right because the engine ran fine upon cold start up until I shut it off after about 20 minutes.  It would not restart (as usual).  Since the primary resistance increased when hot, I suspect the coil is the problem.  If my digital voltmeter is off a bit that would account for 2 ohm reading, vice 1 ohm on the primary.  Any thoughts?  Can the spark plug lead be removed from this coil?  It has a separate part number (NN10729) so I suspect it can.  I fiddled with it a bit because I wanted to take it off to test separately, but I couldn't get it off with minimal force.  According to Jack's Small Engines, that spark plug lead has been discontinued.  

 

Is there any additional testing I should do?  Thanks a lot for all of the help

[Handy Don 10,743]

If you measured the Ωs through the spark plug wire, you can expect slightly higher resistance. Your meter may be accurate.

 

Not familiar with this engine so I can't advise on the wire being removable

[Calvin Jones 4]

Thanks Don for your input.  The slightly higher resistance was measured through the primary winding.  The test via the spark plug wire is the secondary winding.  That measurement was infinity (open), which makes no sense to me because the engine starts and continues to run fine until I shut it down.  Then it will not restart until it cools down.  Test points I used for the secondary winding test was from plug wire cable to the coil iron core.  

[lynnmor 6,850]

Maybe this coil will work.

 

[Handy Don 10,743]

11 hours ago, Calvin Jones said:

Thanks Don for your input.  The slightly higher resistance was measured through the primary winding.  The test via the spark plug wire is the secondary winding.  That measurement was infinity (open), which makes no sense to me because the engine starts and continues to run fine until I shut it down.  Then it will not restart until it cools down.  Test points I used for the secondary winding test was from plug wire cable to the coil iron core.  

Wish I knew more about this engine. Seems like it has both a magneto (to the spark plug, no points) and a stator (via 14v 20a regulator for charging and accessories).

I see the spark plug wire and the small black lead with the Packard connector. What is in the sheathed connection and to what does it connect?

[gwest_ca-(File Mod) 10,539]

Manual says if plug wire is required replace coil.

This may be for your engine

 

[Calvin Jones 4]

Thanks to all who have contributed to this post.  This is an Onan E125V-N-10964B. Thanks for the supporting manual.  It will come in handy.  Yes, it has a magneto to the spark plug and a stator with a 14volt regulator.  The Packard connector in the sheath goes to the regulator center connection and the other end goes to a red connection that has a constant 12.8 Vdc source.  One end of the other wire in the sheath is hard-wired to the magneto and the other end goes to a dark blue wire using a Packard connector, which shuts down the engine when the key is turned off (kill circuit). The coil lynnmor mentioned as a possibility I don't think will work because it doesn't have the kill safety circuit connection.  However, I think this is a good lead.  I'm going to investigate that company (ASAP) to see if they have a similar coil that would support the kill circuit.         

 

  

[Handy Don 10,743]

3 minutes ago, Calvin Jones said:

Thanks to all who have contributed to this post.  This is an Onan E125V-N-10964B. Thanks for the supporting manual.  It will come in handy.  Yes, it has a magneto to the spark plug and a stator with a 14volt regulator.  The Packard connector in the sheath goes to the regulator center connection and the other end goes to a red connection that has a constant 12.8 Vdc source.  One end of the other wire in the sheath is hard-wired to the magneto and the other end goes to a dark blue wire using a Packard connector, which shuts down the engine when the key is turned off (kill circuit). The coil lynnmor mentioned as a possibility I don't think will work because it doesn't have the kill safety circuit connection.  However, I think this is a good lead.  I'm going to investigate that company (ASAP) to see if they have a similar coil that would support the kill circuit.         

 

  

Hmmm. Color me confused. Do you have a wiring diagram for this engine/tractor that you can post?

 

I fully get the kill connection at the magneto, but having 12vdc wiring involved seems odd. (The center of the regulator is the 12vdc supply to the tractor from the running engine.)  Perhaps it is simply that the sheath/loom is housing the regulator-to-R terminal connection (your mention of a "constant 12.8vdc source"--the tractor battery?) along with the "kill" wire and otherwise has nothing to do with the magneto?

[lynnmor 6,850]

The coil I showed was mentioned on another tractor site where it was said to be a substitute, I have no clue if it will work.  I see that the laminations are exposed in the center, unlike the original.  Perhaps there is a terminal for the kill wire hidden from view.

[Calvin Jones 4]

You are exactly right.  The sheath houses both the kill circuit and independently the regulator to the battery (Red connection).  Sorry for the confusion. Wiring diagram attached 

p5-21 to p5-25 1990 212 Onan.pdf

[Handy Don 10,743]

Thanks for posting the diagram and clarifying the routing, Calvin.j

Your testing sequence sounds sensible to me, as well, to eliminate the coil as a suspect before the ignition module, even thought the module seems the more likely failure. IMHO, coils don't fail easily in normal use whereas the electronics in trigger modules are more vulnerable to aging and repeated heat/cool cycles.

 

The constraints to substituting another coil seem to be getting the right output and a reliable (an non-destructive) connection for the kill switch. I don't have experience to share on doing this--sorry.

 

The only "specification" I've seen for magneto gaps (except for Tecumsehs which have pins sticking out of the flywheel) called for using a business card to set the gap. 

[Calvin Jones 4]

Problem resolved!  I contacted ASAP (Advanced Service and Parts) about the substitute coil as lynnmor suggested.  Although it may have worked, I found out they carry the actual ignition coil for my engine for $160. It doesn't show up when you search for it on their website.  Although it was significantly more expensive than the possible substitute ($31) I decided to go with it.  Engine now runs and starts as it should. 

 

I appreciate all of the help from those who contributed to the resolution.  I learned a lot about the ignition system of this Onan.  Frankly, I like the Kohler on my 314-H much better.  My experience has been that parts for it are cheaper and easier to find.

 

     

[Handy Don 10,743]

Thanks for circling back with the solution and good news, @Calvin Jones