John Deere 40

jerryinga · Jan 4, 2017

Once again I am in need of help I am currently working on a JD 40 I purchased a couple months ago. The tractor is running rough. I have had the carburetor rebuilt by Yesterdays Tractor, replaced all the wires, plugs, points, condenser, rotor and cap I have set the timing adjusted the valves and it stills runs rough. It seems to be skipping (but not steady) and is more noticeable at full throttle it is popping slightly. With the muffler off you can see fire coming out of the manifold. Where do I go from here

Thanks Jerry

Den N Ms · Jan 4, 2017

Jerry,It sounds like it is running lean on the fuel mixture.Open up the main jet 1/4 turn and give it a try.

Russ from MN · Jan 4, 2017

Could be a burned valve. Have you checked compression?

Dave H · Jan 5, 2017

Is that "fire" coming out of the manifold a glow or just z pop of fire when it misses?

I have seen them glow if the timing is set on TDC instead of Spark.

ET · Jan 5, 2017

I agree, it sounds lean.

Mike M · Jan 5, 2017

the LOAD mixture screw on them seem to need to be turned out farther than you would think to get them to run right. And the idle screw on those works backwards as it adjusts the air. So in will make it richer.
Without hearing it though it might just be normal. They don't call them popping johnnies for nothing.

jerryinga · Jan 5, 2017

The flame is only when it pops also I have noticed the top of carburetor and the lower part of the manifold is cold and sweating. Am I right back the load out to richen. Could it be clogged fuel filter causing it to be starved for fuel

buickanddeere · Jan 5, 2017

swapped plug wires or a worn distributer bushing.

jerryinga · Jan 5, 2017

New plug wires and distributer good

Hotflashjr · Jan 5, 2017

I am with B&D. If it isn't doing it all the time I bet you have a worn distributor bushing and it is allowing it to skip out of time, every now and then, ever so slightly.

The key is pick one thing and work on it. Work on just the fuel first and if that doesn't fix it then go to the timing/distributor. If you start messing with both at the same time you will make a troubleshooting nightmare for yourself.

jerryinga · Jan 5, 2017

One other thing that might help us find the problem
I never have to use the choke and it cranks first time every time

Russ from MN · Jan 5, 2017

Like old always says, take the drain plug out of the carburetor and it should flow a steady stream into a coffee can forever!

BushogPapa · Jan 6, 2017

BUT, since he never needs to choke it, I say the Idle is set a little too rich also...

I can set my 630 just a little rich ( Idle) and it will start Cold on the 1st turn..But, set "correctly", I need to choke that bad Boy Hard to start it ..!

jerryinga · Jan 8, 2017

Got a chance to work on the 40 this afternoon
This is what I came up with the Load set at 1 1/4 and the idle completely closed
I am wondering if the carburetor rebuild was bad It runs pretty good at this setting but I know that's not correct what's going on

BushogPapa · Jan 9, 2017

At no time will the Idle be set Closed...

I would double check the Carb and be SURE ALL passages are open..

John Deere 40

jerryinga

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Den N Ms

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Russ from MN

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Dave H

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ET

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Mike M

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jerryinga

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buickanddeere

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