John Deere B 1946 stumbles under increased load

vincegsc · Oct 20, 2015

My tractor stalled a while back and it wouldn't start. I put in new points, condenser and rotor. Then put a kit in carb. Now, it starts immediately, idles and runs smoothly. When bushogging, and hitting heavy grass, tractor stumbles with a little darker exhaust. Have gone up a little and down a little on the power screw adjustment. Any suggestions?

Den N Ms · Oct 20, 2015

Vincegsc,Try setting the power adjustment while the engine is running full throttle.Slowly turn it in till you hear the engine go lean and slow down and start to miss.Then open it back up 1/4 and try under a load if still lean open up another 1/4 turn.

vincegsc · Oct 20, 2015

(quoted from post at 16:49:37 10/20/15) Vincegsc,Try setting the power adjustment while the engine is running full throttle.Slowly turn it in till you hear the engine go lean and slow down and start to miss.Then open it back up 1/4 and try under a load if still lean open up another 1/4 turn.

Thanks, unfortunately, I don't have anything to use to apply a belt load.

RandyB(MI) · Oct 20, 2015

It should puff about three puffs of slightly darker exhaust whenever throttle plate is opened quickly, whether by you throwing throttle lever open or governor doing it because of load. It should clean right up clean then. Turn in load needle until it cleans up. If it was flooding itself inside , it would do it at idle also,which it doesn't. If it hasn't been firing strongly before the changes, it may have fouled the plugs.

James Howell · Oct 20, 2015

You might consider removing the oil cup from the bottom of the air cleaner body.

If your tractor runs better under a load, then there might be some blockage in the air stack.

Take a look at the photo below of "Uncle Earl" our 39B and "52" our 52A.

Dirt/mud dauber nests in the air stack can cause similar problems as you have described.

Hope this helps.

vincegsc · Oct 22, 2015

Thanks for all suggestions. It's working, but I'm confused. Directions with carb rebuild kit says set power needle open one turn to start. With Bushog, tractor tried to stall when grass got taller. So, brilliant me turned needle more open. It seemed to be a little better. Based on suggestions here, I pulled plugs. They were light sooty black (running too rich), when previously they have always been light grey. I then ran tractor full throttle, but with no load, turning load needle in. It went all the way in without engine stumbling. I set it at 1/2 turn out. With Bushog, tractor ran OK. I hooked up my model 44 2-bottom. Plowed OK in first gear. Went up to second gear and tractor stalled. Opened needle a little at a time, trying to plow. Ended up a little over 1/2 turn open (about 200 degrees).

Wemedeeres · Oct 23, 2015

Does your tractor have a coil? If so try replacing that, I was at plowing bee this summer and my A was acting similar to yours. I'd been through the carb earlier in the spring as well as replacing points and condenser. It'd idle fine but as soon as I dropped the plow in the ground it would cough spit and sputter, I was convinced it was the carb and so were a few of the old timers that were there. I loaded up hanging my head in frustration, got home and replaced the coil and she hasn't missed a lick yet!

John Deere B 1946 stumbles under increased load

vincegsc

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Den N Ms

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