Farm Equipment - D12 Carb issue?

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D12 Carb issue?

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=37749
Printed Date: 27 Sep 2025 at 5:20pm
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Topic: D12 Carb issue?

Posted By: Tracy Martin TN
Subject: D12 Carb issue?
Date Posted: 22 Sep 2011 at 6:59pm

After rebuilding carb on early D12 it ran pretty great for a while. while plowing it has started acting up. It only wants to run with choke on. You can put your hand over breather tube or open choke and it sputters and dies. Tank is clean. What is most likely causing this problem? Thanks Tracy Martin

Replies:

Posted By: Dave Richards (WV)
Date Posted: 22 Sep 2011 at 7:10pm

Tracy, check to see if mixture screw backed itself out. Sounds like an air leak somewhere. However, bad fuel flow will do this also. As in a clogged jet. On my D14, it needed half choke all the time from when i got it. Didn't have a kit so I just took the carb apart, cleaned everything and put it back together. (three times cause i always had parts left over) Ran really great for a few months then the same fuel starvation problems. Second time I cleaned it, I noticed little black scuz balls in the bowl. Turns out, the ethanol in the gas had worn out the rubber fuel line. Replaced with new and it"s just great again.

Posted By: Thad in AR.
Date Posted: 22 Sep 2011 at 7:26pm

Tracy I got an acorn in the tank on my D14 once. It would run good for a while then it would roll in a bad spot and shut down the fuel flow. I cleaned everything several times and always checked fuel flow through the line and always had fuel, just not enough.

Posted By: Tracy Martin TN
Date Posted: 22 Sep 2011 at 9:34pm

Tank is clean as a whistle. It will run well wide open with choke on, slide it forward it will sputter and die. Really doesn't want to start unless choke is on. With hand over breather pipe it runs well, take it off, and it dies. It has me puzzled. Any suggestions? Tracy Martin

Posted By: BV
Date Posted: 23 Sep 2011 at 9:22am

Tracy my D10 did the same thing and it had a piece of trash inside the sediment bulb causing my problem. Take it apart and blow it out , maybe you have the same problem.

Posted By: Dusty MI
Date Posted: 23 Sep 2011 at 10:41am

I had a problem with my D-10, it ran great, but I went on a 2 day tractor caravan in Augest last year when the weather was hot. Started in the morning when it was cool, it ran great. But by break time the weather had warmed up and the carb had heat soaked durning break. The D-10 ran tearable after that. Tried a new coil, no help. Did a carb field strip under a shade tree while the others ate lunch, no change. Had to ride the trailer for rest of trip. The only good part of that is you get to see the country better, and take more pictures.

A few days latter I again took the carb apart on the bench with the book in front of me. The float bottom stop was adjusted way up to where it only had about 1/64" of travel. There fore the heat thinned gas that trickeled into the carb could not provide enough BTU's to the engine.

Dusty

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917 H, '48 G, '65 D-10 series III "Allis Express"

Posted By: Chalmersbob
Date Posted: 23 Sep 2011 at 10:18pm

I had that problem on my D14. Run greeat with the choke on, died with it off. Had a leak in the intake manifold. You can spray around the intake manifold with carb cleaner or brake cleaner and see if it changes the way it runs. Bob

Posted By: Dusty MI
Date Posted: 24 Sep 2011 at 8:08am

Pull the plug from the bottom of carb and do a flow test.

Dusty

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917 H, '48 G, '65 D-10 series III "Allis Express"