Need help troubleshooting my 875

[Ponyboy 64]

Good evening, all

 

I had taken my 875 out of her stall for her inaugural blade cutting last weekend. I got through 2 laps and she died on me while driving (the engine stopped running). I'm pretty sure it's an electrical issue but I can't pin it down.

 

K181s engine

 

What I've done so far

• She turns over fine but is not catching
• Full fuel tank, I confirmed lines aren't clogged and fuel pump works (also doesn't catch when I spray starter fluid into chamber, also leading me to think electrical)
• Fully charged battery
• 12v registering at +lug on coil (actually about 12.49) with ignition turned to on
• Just bought a cheap ($8.50) in-line spark plug tester that is not lighting up when I plug it in and turn the engine
• Coil lead test OK for continuity (coil + lead ~2 years old)
• Condenser seems ok (voltmeter test)
• Cleaned points, re-gapped to .020 (points ~2 years old)
• New spark plug, gapped to .025

 

She fired up 1st try last weekend after sitting all winter, like she normally does.

 

Is there any other way to test the coil? 

 

Thanks in advance for your help!

 

[Pullstart 62,884]

Hey, I’ve got an aunt in Dallas, OR!  Sorry I got caught up in that… 

[Pullstart 62,884]

It would be a good idea to measure the voltage at the coil WHEN CRANKING.  I have had failed ignition switches give power when ignition is on, but not when cranking.

[Handy Don 12,232]

15 minutes ago, Pullstart said:

It would be a good idea to measure the voltage at the coil WHEN CRANKING.  I have had failed ignition switches give power when ignition is on, but not when cranking.

Good idea

 

@Ponyboy If the switch seems bad, you can temporarily “hot wire” a jumper from the battery positive to the coil around the switch to get ignition and then use the starter to crank it. Just be sure to remove the jumper to shut down the engine!

Edited March 25 by Handy Don

[Blasterdad 2,692]

33 minutes ago, Ponyboy said:

(also doesn't catch when I spray starter fluid into chamber, also leading me to think electrical)

 

NEVER use starting fluid on these little engines, BAD things can happen, i.e. blown head gasket, hole in piston,ect... Use a squirt bottle with a little bit of gasoline in it. 

 

[WHX?? 48,815]

31 minutes ago, Blasterdad said:

Use a squirt bottle with a little bit of gasoline in it. 

Or most brake/carb cleaners. 

[RED-Z06 2,221]

If you have 12v to the + side of the coil and you touch a grounded wire to the - side, the plug should spark..if it doesn't, bad coil.  If the points are closed and the key is on, the coil can overheat fairly quickly and at minimum...fail

[953 nut 55,230]

Here are a couple of coil tests that were posted years back by @Save Old Iron that work well.

 

[squonk 41,118]

11 hours ago, Ponyboy said:

 

• She turns over fine but is not catching

 

Does it sound normal when it's spinning over? The normal WHOOMPA WHOOMPA WHOOMPA? Or does it sound like it's spinning real fast?

[D_Mac 8,619]

I had a problem with spark on my 875 once. It had random spark. Turned out the wire from the points to the coil was bad. Good luck with it.

[Ponyboy 64]

Thanks for all the replies!

 

I went out and removed the coil from my K181 and set my multimeter to ohms. Checking both the primary and secondary windings, the number never changed from 1, regardless of what ohms setting I was on (I have settings from 200 to 20M Ohms). Is that a sure sign to get a new coil? Would/could a coil just go out during a regular mowing run (and if not, is there something else I should be looking at)?

 

I'm assuming there's some sort of liquid (oil?) that's supposed to be in the coil, correct? I never noticed before, but it sloshes when you shake it. No leaks or anything, just heard it slosh when I was carrying it to the barn to test.

 

And to answer squonk's question, engine sounds just fine/normal when churning (the normal WHOOMPA).

 

And lastly, any good sources for a new coil? I got this one from I Save Tractors about 2 years ago, maybe has 16 hours on it. I can do some searching but curious what others on here use.

[squonk 41,118]

You need an internally resisted coil. Napa/Echlin  # IC14 or equivalent.

 

[Ponyboy 64]

Just picked up that Napa/Echlin coil and installed it, started right up 1st try! Thank you all!

[Fordiesel69 263]

They fail quite often.  I had a stack of 6v coils I got for free, and they last 1-2 mowing seasons on a 12v system.  They get blistering hot.  So hot they lose all their paint.  

[953 nut 55,230]

6 hours ago, Fordiesel69 said:

They fail quite often.  I had a stack of 6v coils I got for free, and they last 1-2 mowing seasons on a 12v system.  They get blistering hot.  So hot they lose all their paint.  

That is why you should use an ignition ballast resistor on a 6 volt coil. The coil Mike @squonk recommended has an internal resistor just like the factory Kohler Coil has.