Help, tractor starts, wont run properly

Hi guys,I have an old 8N tractor that had been running fine. It started spitting and sputtering, backfiring etc. I've had issues with the points before so that's where I started, new points. That didn't help. So far I've done the following, lol.

Replaced front mount distributor with new one, new cap, new coil, new points, condenser, rotor cap, ballast resistor. New plugs, new plug wires, checked and double checked for correct plug wire placement, it's all correct. Same problem, cranks, idles ok for a bit then starts spitting and sputtering. Replaced gas tank because the old one was rusted and needed replacing anyway, new fuel filter, new carburetor. Checked all wiring, checked compression, it's all fine and it's still doing the same thing.

This was originally a 6 volt system as were they all and I was seeing 12 plus volts at coil, I thought it was supposed to be somewhere around 8V so that's when I changed the ballast resistor thinking maybe it was bad, didn't help.

I'm at a loss, the only thing that hasn't been changed is the governor but I thought the governor was basically to keep it from over-revving.

HELP!

I've also checked the spark at the plug, 1/4, nice and bright. The plugs do seem to be sooty as all git out already though.

Wow.

That's amazing.

I can't think of any thing left to replace, perhaps other than the stale air in the tires.

There are two schools of thought when it comes to getting a non-running tractor to start. One way is to just start replacing every part you can get to until it starts or you run out of money. The other way is to take a step-by-step approach to solving the problem, working from most likely to least likely. 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 step by step and work from most likely to least likely. You have turned a simple troubleshooting problem into an expensive and time consuming exercise that now vastly complicates the troubleshooting due to all of the new parts. Which may or may not be up to oem specs or installed correctly.

So........

Front or side distributor?

Don?t continue to guess at the cause of the problem; guessing can get expensive. Troubleshoot the problem.

As soon as the tractor starts running rough, not 5 minutes later, check for spark and fuel.

You need to answer 2 questions before you do anything else:

With the bolt in the carb bowl removed and the gas on, will the fuel flow fill a pint jar in less than 2 minutes?

Next, get out your adjustable gap spark checker * , open the gap to 1/4", hook it up, turn the key on and crank the engine. Does the spark jump 1/4"? Post back with the answers.

And do not buy a new part for the tractor until you can answer this question: how do I know the part on the tractor is defective?



* Don't own an adjustable gap spark checker? Buy one! Not a test light! Until then, take an old plug, open the gap 1/4" ground it to the head & look for spark. It?s not the color of the spark that counts; it?s the distance it jumps.
75 Tips

Platt........sooty plug is RICH carburator. Learn how to adjust yer carbie. Set yer down-pointing MAINJET to 2-turns and LEAVITT!!! Adjust yer side pointing IDLEMIX fer FASTEST idle NOT SMOOTHEST idle. Understand the difference??? Shuld be about 1/8-1/4 turn. Adjust the behind the carbie idle speed set to ennythang under 500-rpms. Don't haffa tacho? Buy an el-cheapo and runner on 9-volt battery. Simple, eh?.......carbie Dell

Compression test ? Possible valve problem?

Which fuel filter did you change? There should not be one in the fuel line...

Have you tried new fuel? Not some from your bulk tank, but new from the station in a clean can..

Back to fuel again. You did not put diesel or kerosene in it by chance? Sooty plugs = diesel.

(quoted from post at 19:26:01 10/14/17) Back to fuel again. You did not put diesel or kerosene in it by chance? Sooty plugs = diesel.

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No, no deisel or kerosene.

To the rest, yeah I've replaced the points enough times to know how to troubleshoot the electrical aspects. There's good fire getting to the plugs. Yes I've checked the compression. Yes I've rebuilt one carb and installed one new one. Yes, yes and yes again. I've had the tractor long enough to become pretty darn familiar with the simple little SOB, lol.

I worked in the telecom industry as a trouble shooter for 40 years so I'm pretty familiar with trouble shooting techniques and after performing those techniques threw up my hands and starting buying new parts.

I feel sure it's something pretty simple that I'm just flat out missing or looking past.

The only thing I didn't try was removing the bolt from the bottom of the carb to make sure I was getting a good gas flow so I'll try that.

Thanks for all the suggestions guys! I really appreciate your time. And keep them coming please!

Yep, 1/4 inch and 1/4" arc. I did not try the gas flow check so I will, Thanks!

So, since you had had experience with old points giving you these symptoms and put in new ones that do the same. Good start! Now did you verify that the new points were any better than the old ones you took out? Check that they are properly aligned (I've had a set that didn't), that they make good contact (some don't right from the factory), and that the point gap hasn't changed (some rub blocks are too soft and wear down on the cam lobe).

(quoted from post at 04:46:09 10/15/17) So, since you had had experience with old points giving you these symptoms and put in new ones that do the same. Good start! Now did you verify that the new points were any better than the old ones you took out? Check that they are properly aligned (I've had a set that didn't), that they make good contact (some don't right from the factory), and that the point gap hasn't changed (some rub blocks are too soft and wear down on the cam lobe).

Click to expand...

Yep, all the above. Opens and closes properly, gapped correctly and both nodes line up.