The first thing to do, just to say you did, install new plugs.
I have chased problems needlessly just like this and the problem was solved by replacing perfectly good looking plugs!
Choke assist can be deceiving, it can remedy both lean condition and weak spark.
Wouldn't hurt to take the carb off, ease the bowl off, take a look, clean it out, clean the main jet with a stiff wire. Just spraying and blowing will not remove dried ethanol residue, it has to be scraped out of the jet, down to bare metal without actually enlarging the hole.
But, usually a clogged carb will not be intermittent, it will run or not run. Fuel delivery can be intermittent. Water in the fuel can be intermittent. Look for rotten fuel lines, pieces of rubber can flake off the inside and clog the fuel pump, cracked lines can suck air. If there are 2 tanks, the change over valve can suck air.
The spark... Removing either wire should make a drastic difference. At idle removing one wire may kill the engine, but up to speed it would make a noticeable difference. If removing one wire does not make a difference, check that wire for spark delivery. I like to use a test light, it won't make the light light, but it makes a safe insulated handle (with the other end grounded) to stick inside the boot and observe the spark. Running up to speed it should easily give a 1/2 inch or more spark. Remember, you have to catch it in the act to prove anything.
If you do find weak or no spark, open the top cowling and unplug the kill wires from the coils, replace the cover, take it for a trial run. Just be aware once started the ignition nor safety switches will not stop the engine! If that solves the spark problem, look for a shorted wire to ground, or some have a diode in the wire between the coils. A shorted diode will kill one or both coils.
While the cowling is off, be a good time to clean out the cooling fins, and check the intake bolts, be sure they are tight an no sign of vacuum leaks.
Another possibility could be valve problems. A loose valve seat can cause intermittent compression problems. But save that for last! Not sure if that has solid or hydraulic lifters, need the model and serial numbers to research that. If solid be a good time to set them by the book procedure, don't guess!
Upload one or more videos to your post. Photo and video filesizes should be less than 5MB. Formats allowed are gif, jpg, png, ogg, mp4, mov, and avi. Be sure to use filenames without spaces or special characters, and filetypes of 3 digits lower case.
We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]
Today's Featured Article - Preventing Tractor Theft - by Staff. The discussion started with the following message: I have a JD A without key start or any locking device. Is there a best way to secure it so the chances of it being stolen are reduced? Following are some of the answers that were received: Take the rotor out of the distributor and hide after each use. The would-be thieves at least couldn't just get on and drive away.
... [Read Article]
Latest Ad:
1965 International Harvester McCormick Farmall cub tractor 2,500. Two owner tractor. My grandfather bought new in 1966, then we inherited it. Have all the paperwork original manual and all maintenance records. It starts and moves. Comes with underbelly mower, plough, and some other attachments.
[More Ads]
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy
TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.