106-check my diagnosis

[jbrewer]

I was working on getting my 106 running...I've done little with it since I got it (it ran well), other than the last time I tried to start it (3 mos ago?) it would NOT start, NOR WOULD IT STOP CRANKING. I had to quickly unbolt the battery lead to get that stopped. It does NOT do this all the time.

Another clue -> Previous owner said "I hooked up a 12V light to the + of the coil to groundbecause I've had trouble getting spark intermittently and it's a good diagnostic aid". Hmm.... reeks of shade tree, but for the time being it's still there.

Today... I tried to start it and there's no spark. I cleaned and verified point action (no problem) swapped coils (no difference) temporarily removed the condenser (no difference) , swapped spark plug cable (no difference) , and put in a new plug (no difference). There was voltage to the primary of the coil (the diagnostic light bulb was lit)

I noticed ONE thing...when I released the ignition switch (from the crank to run position) I saw a spark plug spark...but ONLY as the engine was coasting down and the key was in the RUN position.


I'm thinking now that the ignition switch is bad. That would account for the PO's observation of occasional spark problems, the "run on" starter sequence, and the lack of spark in the "crank" position... I think..... BTW, the solenoid looks new, as if it was replaced by the PO.

I do NOT recall if the "trouble light" was on when cranking (Doh!).

Do you agree with my diagnosis?

John

[mrcubcadet]

Sounds like the ignition switch is the only thing left, to me!



But, I would get a wiring diagram and check to make sure each ignition switch post has the right wire going to it.

[cub123]

I agree that it sounds like the key switch, my 106 does that ( wrong key switch) you have to release it to ON for it to fire.

[Vince_o]

Its wired wrong. Check the switch to the celonid. You stated it wouldnt stop turning over when you first got it.

Look at the wiring dia and the v/r are hooked up right. Theres a wire crossed, but cant remember if it was on the switch or the coming back from the Vr.

If I remember right it was Roland that helped me with that problem many yrs ago, maybe he will see this and chime in. I know he will send you the dia for it.

[darkminion_17]

Try changing the wire to the points if not done already.The run on issue could be your ignition switch or the voltage cutout relay in the vr is sticking.

[Jeff in Pa]

Here's the wiring diagram for the 106 ( last one at bottom of page)
http://onlycubcadets.net/forum/showthread.php?t=35

[jbrewer]

Is there any potential for damage by taking a jumper from battery to + coil and a heavy jumper cable from battery + to the A terminal of the S/G just to check everything else other than VR and switch?

[jbrewer]

Meanwhile , back at the 106...

Charged up the battery , fixed the fuel leak at the sediment bowl , hooked up the battery and noted no spark upon making the connection.

I cranked it, and noticed that the ignition test lite on the + of the coile was OFF while cranking. I also noticed that the starter stayed ON once I turned it over, regardless of key position. When removing the battery lead (I was ready this time) it sparked as there was a load on it when disconnecting, naturally.

I'd suspect the relay (which it might indeed be) except for the fact that the relay should NOT prevent 12V from going to the coil , as a faulty ignition switch would. The relay looks new (I suspect I'm not the first person to trouble shoot this. ).

So, when I get some time I'll trouble shoot this some more with a voltmeter on the starter relay control voltage (I think I'll slip the belt off the S/G too!).

Or I could swap parts.... I do have a generic starter switch with 3 connections. As with all good mysteries there's a few leads that aren't connected to anything...

John

[save_old_iron]

John,

sounds like multiple problems on the tractor, especially since there are "a few leads that aren't connected to anything".

Regarding the continuous cranking / no spark issue, YES, the regulator can be causing this. I'm working on a 104 right now and should be able to post a few pics later to help you out better.

For now, understand there is a very good chance the contacts in your regulator's CUTOUT relay may be sticking together. This creates a "backdoor" for current thru the relay contacts to the starter function of the SG unit.

With the regulator connections facing you , cover off, the CUTOUT relay should be the one on the far left.









The contacts on the relay should normally be OPEN. If they are not, or are extremely pitted, the relay will allow battery voltage back the the relay to the armature wiring.

If you check the contacts on an un-powered regulator, 2 relays should have their contacts closed and the CUTOUT relay contacts should be open.
If the CUTOUT relay contacts are closed, you might be able to GENTLY pop them apart









and inspect the contacts. The contacts will most likely be severely pitted

[Matt G.]

That series has wiring harnesses that deteriorate badly after 40 years, so the first thing I would do is re-do the wiring harness. It also sounds like the ignition switch could be bad, which is easy to check with a multimeter.