8n dies after working great suddenly

So in a previous post I was having problems with my 8n not starting. I replaced the starter solenoid and the carb and she started right up. Brush hogged my yard and started in the overgrown field behind my
house (probably 2 acres total work and a few hours work) and she just died. No warning, not a stumble, not even like I hit something that put too much load on the tractor. Just sputtered 2 times and died.
Refused to start after that.

I thought the battery was the culprit and I replaced the very old battery with a new one. Still no start.

Starter motor sounds strong. Gas seems to be getting to the carb. This tractor was converted to a 12 volt side alternator setup by someone else. I am having a hard time figuring out things on it after the
conversion and seems like I am getting some gremlins in the electrical.

Any advise on field trouble shooting? Maybe needs spark plugs but it is just weird that it was all working fine and honestly like new after the starter solenoid and carb replacement then just died.

Oh and I did check the gas. there was a full tank.

The primary reason your tractor isn't running is because you are just randomly replacing parts instead of troubleshooting the problem.


In the 50+ years I've been working on old cars & tractors, I've tried a number of different methods to get a non-running car/truck/tractor to start. One way was to just start replacing every part I could get to until it started or I ran out of money. Another way was to take the advice of my well intentioned, non-mechanic friends who would tell me that when their vehicle had the same symptoms, it was the whatever that was broke or needed adjusting. I'd then try that, usually w/o getting it to run. But, when I was occasionally successful, from that point on, every time the vehicle had those symptoms, I was confident that the same fix as before would work again. It usually didn't.

Your friends (and maybe your experience ) will often get in the way of fixing your tractor. Rarely are guesses like "It's the coil" helpful. We can make a long list of possible causes for the tractor not running and start picking our favorite to check out. Or, we can step back and recognize that the trick to fixing these tractors (or trouble shooting any piece of equipment) is to be systematic about it. You need to isolate the problem system by system, step by step and work from most likely to least likely and replace parts only when you confirm they are defective. Jumping ahead to 'so-and-so said it could be whatever' or just replacing parts usually just wastes your time and your money.


It takes three things for an engine to run: spark at the right time, compression, & gas/air in the right mixture. Compression is easy; check it with a gauge. But, you don't lose compression overnight, so if your tractor won't start, or suddenly cuts off, forget about compression for the moment, & concentrate on narrowing the problem to fuel or spark. If you don't do that, you are going to end up chasing your tail around that tractor & spending a boatload of money to fix what could easily be a loose wire or a clogged fuel tank vent. I offer this advice from personal experience because I am not a magician. I do not have the magical ability to simply diagnose the problem & go right to the fix. So, whenever my tractors stop, I check spark & fuel then go from there.

I might not be capable of telling you why your tractor isn't running, but I sure can tell you how to figure it out for yourself.

Bottom line:

Does the tractor have a spark that will jump 1/4" in open air?*

Will the gas drain out of the carb bowl in a steady stream and fill a pint jar in less than 2 minutes?

How do I know this part is defective?

These are the questions you need answered before you attempt any repairs or buy a new part.

Post back with what you find after you check for spark /7 fuel. (see tip # 13 to see how to do that)


*If you don?t own a spark checker w/ an adjustable gap, buy one. In the meantime, an old spark plug w/ the gap opened to at least ?? will work. Ground it to a rust & paint free spot on the engine turn the key on & look for a spark.
75 Tips

ruttdigger.......instant engine stop, eh? That's always electrical. Me? 8N's have a weak sister ignition switch. I replaced mine 3-times one summer, just brushhoggin the lane. Gott gryped (PsOf) went down to marine store and botta WATERPROOF 25-amp toggle switch. NO PROBLEMS since. The factory key-switch is rated 5-amps and ignition circuit draws about 3-1/2 amps. Quality control ain't what it used to be, eh? ........electrical Dell

Yep, he could drop another $25 on a quality switch w/o checking the one that's on the tractor.

I'm not in the habit of replacing parts until I confirm they are defective. And I don't recommend that others do it either.

immediate stops USUALLY turn out to be electrical, or at least ignition based, even if mechanical ( IE.. rotor breaks, distributor stops spinning ).

First thing you do is check spark, and go from there.

Thanks for the replies and for the 75 things to check.

I should have said that I replaced the starter solenoid and carburetor because I for sure knew they were bad and the carb wasn't worth rebuilding. I am really just trying to get a direction to start checking for the next weakest link. I tend to think ground issue but I was thinking that some of you with much more experience with the 8n could help. Plus there is a 12 volt conversion that really doesn't make much sense to me and makes finding or tracking down electrical issues a pain. Really eventually I want to either go back to 6 volt or rewire correctly but in the meantime I need to make sure I can clean up my lot for work.

I do want to totally redo the tractor just want to be strategic about the order for now.

[b:61fba3f759]"Plus there is a 12 volt conversion that really doesn't make much sense to me and makes finding or tracking down electrical issues a pain. Really eventually I want to either go back to 6 volt or rewire correctly but in the meantime I need to make sure I can clean up my lot for work."[/b:61fba3f759]

perhaps if u were to explain the situation in detail, folks here could help u to understand what the state of your wiring actually is. u say it doesn't make sense to u, but then u say u might want to rewire it correctly. what makes u assume it is wired incorrectly?

12 volt conversion or not, the wiring on these tractors is about as straightforward as any motor vehicle wiring gets. there should be no reason to need to guess.

[b:61fba3f759]"I replaced the starter solenoid and the carb and she started right up."[/b:61fba3f759]

unless u redid your wiring after it successfully started up, i'm not clear on how it would be wired wrong.

for example why have all this wired up with 2 starters and a key and not use the factory starter button

Unless you changed the wiring, it ran before and it will run again . Google " wiring diagrams JMOR" and find the one that fits your tractor.

Meanwhile, have you checked for spark and fuel?
75 Tips

Ground issue???

Don't play guessing games.

Check for spark and fuel and tell us what you find.

Ruttdigger. have you tried hooking up the white wire that is disconnected in your picture? Looks like it hooks to the ballast resister. HTH

If your tractor was running fine and just suddenly quit I would try taking a voltage reading at your coil with the switch turned on. I suspect you lost your voltage for some reason. If you have voltage there then sounds like either your points froze up or your fuel quit.

may be totally off base, but at this point in your investigation of the problem, nothing should be off the table.

my old tractor just stopped running one day while I was disking,
it was the coil, as the coil got hot, located by the block on my tractor, the broken wire separates and stops the motor,

after the motor cooled off it started right up, this made it hard for me to trace, since it stop running, then starts running again.
I check everything I could, all looked good, gas electrical, so I just on a whim replaced the coil and it fired right up.
I was fully prepared for it to stop running after the motor warmed up, but it didn't, it kept running and that was years ago.

was just a chance thing, as I am a parts changer mechanic.

good luck and let us know what you find wrong with your tractor, someone else may have the same problem this summer.