(800) 853-2651
SHOP NOW

Backfiring

A

Anonymous-0

Well-known Member
I just re-timed a 1952 M for an old fella down the road.He has had this tractor for over 10 years and whomever had it before him had the timing really out of whack,but it still ran, but ROUGH. It almost sounded like an old "poppin johnny".Anyways i set the carb settings to factory specs. I have the main jet 3 turns off the seat.The tractor starts perfect-idles perfect and runs fine at full throttle.When you idle it down and shut it off, it backfires. I have turned the main jet screw in to lean it out 3 times at 1/4 turn each time and it still does it.What am i missing here?
 
I would ignore it. The fact that it was operating for years out of adjustmant is reason enough for carbon to be built up to the point that it ignites unburnt fuel in the exhaust.
Let it idle for 2 minutes then shut it off idling. (working it hard with tillage implement of choice for 2 hours will also help.)
Setting the idle speed in the 500 RPM (Slow) is also good. We had a 400 that did it all the time. We ended up Putting it in 4th or 5th and with the brakes on letting out the clutch as the key was turned. No rotation, no backfire. Jim
 
He did go thru alot of spark plugs when it was out of time,now that i think about it.The plugs were always loaded up with carbon.He asked me to adjust the carb 2 months ago so i did. Thats when I discovered the timing issue.The #1 plug wire was going to the #3 cylinder ETC,ETC.They were all messed up.HAHAHA
 
Jim is spot on. Likely to have alot of carbon built up in the combustion chambers. I am willing to guess that if you have the fuel mixture correct and the timing right, it will disappear over time as the carbon burns out. A technique for getting rid of carbon build up was to run the engine up to temp, and use Seafoam or similar poured directly into the carb (on cars) until the engine stalled. Let it sit for 5-10 mins, then start it back up and run it. Only works on down draft or similar carbs, as the up draft style won't pick up enough to stall the engine.
 
I'm a big believer in Seafoam as well. Put at least 1 ounce to every gallon of gas and run it for a tank or two like that after you follow Tom's suggestion.

SF
 
It needs to be worked HARD to blow the carbon out of 'er.

Try spraying the seafoam directly into the intake. Get the engine warmed up good then spray as much in as it'll take without stalling the engine. Shut down and let it soak. Next time you start it, it will smoke like a freight train for a while, but the carbon should be pretty well cleaned out.
 
In addition to what the others have said, particularly Jim's comment, remember that a carb too rich will cause an engine to run rough and emit black smoke; a carb too lean will cause it to spit and backfire. I doubt that, at three turns, you are too lean. But, it is something to factor into your analysis of your situation as you work through it. Mike
 
Red hot carbon igniting incoming fuel. Try misting water into the intake with something like a windex bottle to the point it almost stalls. On the other hand you can also use the seafoam, Again mist it in with a spray bottle, otherwise its pretty hard to ad to the carb at the angle its at.

If I were adding it to the gas, I would dump the whole bottle in the gas tank then fill it.
 
Ah... The most interesting ones are those that let you get off the tractor and get about 10 feet away before it backfires!

When the ignition is cut off fuel continues to be drawn in from the carburetor and out the exhaust. The back firing is the result of unburned fuel being ignited in the muffler. Carbon deposits in the muffler can make it worse. Giving the tractor a good workout may help by getting the carbon burned out of the muffler. A worn out engine can make it worse because the engine will turn over more times until it stops. The only solution is to get the temperature of the muffler lower and/or to have less fuel enter it as the engine spools down. Let the engine idle to cool the muffler and set the idle as low as practical to cut down on fuel.

Electric fuel cut off solenoids were added to carburetors on later tractors to eliminate this problem.
 
You must log in or register to reply here.

Similar threads

R
Carburetor Adjustment, Timing Adjustment or Engine Issue
Replies
2
Views
480
RTR
R
M
TO-20 TSX361 carb questions
Replies
11
Views
807
Mad Farmer
M
K
640 Idles Perfect but Won't Rev Pp
Replies
3
Views
474
KlinkSanford
K
S
Carb issues....
Replies
17
Views
2K
Smokeonthewater
S
M
SMTA carb
Replies
5
Views
286
Matt E.
M
Tractor Parts Tractor Manuals

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.

Copyright © 1997-2024 Yesterday's Tractor Co.

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.

Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy

Back
Top