149 No power to coil

jbeerens · #1 03-09-2026, 09:59 PM

I recently pulled the engine out of my 149 for some work. New head gasket, flattened head (.001 won't fit under it

), static timing on the points, and put a screen on the flywheel (PO hadn't had one on there). I put the engine back in on Saturday and it has no spark!
On the wiring diagram I noticed the points wire was on the wrong coil post so I moved it. It sparked exactly ONE time, when dad still had has hand on the spark plug tester and found out how 48,000 volts feels. Then it went back to having no spark. XD
Because the points wire had been on the wrong coil post, I thought the coil could have possibly been damaged, so I tried swapping in a spare coil. No dice. Next, I connected the + lead from my battery charger to + on the coil, then - on the charger to - on the battery. This still did not work. The starter generator has been rebuilt, solenoid, voltage regulator, ammeter, and condenser have been replaced, and I can verify the contacts on the points are closing and in good shape. The only obvious culprits besides the wiring itself are the coil and key switch. How do I test these parts? Any help would be appreciated, especially since I'm HORRIBLE with electrical parts.

Billy-O · #2 03-09-2026, 11:29 PM

Consult the wiring diagram for your tractor. It is important to properly connect the coil +/- with the points on - side of coil to ground https://www.onlycubcadets.net/forum/showthread.php?t=22

When the points OPEN, the magnetic field in coil collapses, thus producing a spark @ the spark plug.

Also, it's not a good idea to use a battery charger to provide power to coil....especially without a battery presented on the grid. That can harm the coil as the charger can spike voltage. Good idea to test the coil to see it falls within certain parameters: https://www.onlycubcadets.net/forum/showthread.php?t=11

ironman · #3 03-10-2026, 07:33 AM

I have had a brand new set of points cause a no spark condition, and yes they "looked good".
I would suggest switching back to a "known good" set of old points or try a different new set just to eliminate something so easy to overlook.

darkminion_17 · #4 03-10-2026, 09:21 AM

The points need to be cleaned as oil residue is present from the factory. Run a clean dolla bill through the contacts.

jbeerens · #5 03-10-2026, 12:30 PM

The points are not brand new. They are the ones that had been on the engine and had worked well. I did clean them when I did the timing and I can verify that they conduct electricity and are closing. I did a continuity test with a multimeter when timing the engine; points are not the issue

finsruskw · #6 03-10-2026, 01:58 PM

No power TO THE COIL??
Look at/test the ignition switch would be the first thing I would check.

ironman · #7 03-10-2026, 02:28 PM

A bad condenser will also give you a no spark situation.
Disconnect it and check for spark.
AND...
do you have the condenser on the same coil post as the points wire?

jbeerens · #8 03-10-2026, 02:44 PM

Quote:

Originally Posted by finsruskw

No power TO THE COIL??
Look at/test the ignition switch would be the first thing I would check.

Quote:

Originally Posted by ironman

A bad condenser will also give you a no spark situation.
Disconnect it and check for spark.
AND...
do you have the condenser on the same coil post as the points wire?

Yes, no power to the coil. I replaced the condenser this past summer. Shouldn't it last longer than 8 months??
Hot wire from the key switch goes to + on the coil, then both the condenser and points are tied to - on the coil. Is it even possible for the key switch to send power to the starter generator but not the coil when it fails???

Ambush · #9 03-10-2026, 04:25 PM

I just a had a faulty spark plug episode. Thought I flooded it, pulled the plug, cleaned and back in. One or two fires then nothing again. Pulled the plug and when grounded I got about one spark every ten cycles. Held it just off ground and spark jumped from the plug body to the head. Cleaned an old plug and away I went. The plug was good two days ago. Points and condensers can be the same.

ironman · #10 03-10-2026, 05:25 PM

Quote:

Originally Posted by jbeerens

Is it even possible for the key switch to send power to the starter generator but not the coil when it fails???

Well, the key switch is not sending power to the starter/generator.
The key switch is sending power to the starter solenoid.
When you turn the key to start or run, battery voltage is applied inside the switch to the wire connected to the coil.
When you turn the switch to start, battery is applied inside the switch to both the wire going to the coil and the wire going to the solenoid.
Therefore if the contact inside the switch for the coil wire is faulty, you get no battery to the coil.
So the simple answer to your question is Yes.
Corrosion the switch lugs can also create your problem.