Black smoke/stumbling when engaging cluch or reving engine

jwitty

Member
So my john deere b is running great at idle. I can put it in 2nd or 3rd and engage clutch and it won't stumble or puff black smoke. Now when I rev engine higher than idle it struggles to get to its high rpm and also struggles and blows black smoke when engaging clutch. I just cleaned carb (although I didn't "rebuild" it) and it's got new points and condenser with a rotor. Also...when just driving around it runs ok but sounds like it making a puffing sound like it's blowing extra air out of the muffler.
 
What year "B" and what carb ? The '47 and newer have the 67 which has a spring loaded choke that must me "clocked" correctly for proper operation. Sounds like yours is wrong and when throttled up the wind sucks it closed because choke in not in sync with choke lever.
 
(quoted from post at 16:20:33 11/05/17) What year "B" and what carb ? The '47 and newer have the 67 which has a spring loaded choke that must me "clocked" correctly for proper operation. Sounds like yours is wrong and when throttled up the wind sucks it closed because choke in not in sync with choke lever.

It's a 51 and yes it has that spring choke thing. Now that I think of it...when I had the carb off I noticed the choke doesn't open up completely
 
Your accelator ports are clogged on the main nozzle...so when you open up carb it pulls raw gas up the tube and is flooding the engine....much like putting the choke on. Pull the carb main jet and clean it out...you'll have to thread a 1/4 screw into the bottom to pull it out...don't try prying it down or you'll bend the top and destroy it...once you clean it up it will want to fall out...is held in position by the spring..
 
(quoted from post at 17:11:07 11/05/17) Your accelator ports are clogged on the main nozzle...so when you open up carb it pulls raw gas up the tube and is flooding the engine....much like putting the choke on. Pull the carb main jet and clean it out...you'll have to thread a 1/4 screw into the bottom to pull it out...don't try prying it down or you'll bend the top and destroy it...once you clean it up it will want to fall out...is held in position by the spring..

I've already cleaned the carb and made sure it was clean.
 
It may be as simple as an air restriction in the air cleaner due to mud dauber wasp nests not letting a high volume of air thru at higher engine speeds. Mostly in the inlet area, some people put socks over the intake stack to keep the buggers out. Which is way easier than dealing with pounds of dried hard clod removal.
 
(quoted from post at 17:44:05 11/05/17) It may be as simple as an air restriction in the air cleaner due to mud dauber wasp nests not letting a high volume of air thru at higher engine speeds. Mostly in the inlet area, some people put socks over the intake stack to keep the buggers out. Which is way easier than dealing with pounds of dried hard clod removal.

I'll have to look at it tomorrow and clean it out. What's the easiest way to.get the intake out?
 
As per other post check for restrictions...before you work on carb take the bowl off the filter and be sure you're not restricted to the carb....I question this but check anyway....also you could pull the air intake pipe from the carburetor to be sure you're not restricted in air flow....I still think you're pulling raw gas in the main nozzle and it's not meter on throttle up....when you're putting the tractor under load your fuel supply in carb is trying to come through the main jet....you might be able to remove the bowl and then blow air straight up through the main and see if this then helps....but I suspect you'll need to pull the main jet to clean it out....
 
Well then if the choke isn't opening up fully then take the intake pipe off....hold the choke open the throttle it to see if it clears up or does the same thing....before removing carb....any other information as this is critical in diagnosing the problem....
 
(quoted from post at 18:35:24 11/05/17) As per other post check for restrictions...before you work on carb take the bowl off the filter and be sure you're not restricted to the carb....I question this but check anyway....also you could pull the air intake pipe from the carburetor to be sure you're not restricted in air flow....I still think you're pulling raw gas in the main nozzle and it's not meter on throttle up....when you're putting the tractor under load your fuel supply in carb is trying to come through the main jet....you might be able to remove the bowl and then blow air straight up through the main and see if this then helps....but I suspect you'll need to pull the main jet to clean it out....

I have completely cleaned the carb. The main jet is completely clean
 
(quoted from post at 13:23:26 11/05/17)
(quoted from post at 16:20:33 11/05/17) What year "B" and what carb ? The '47 and newer have the 67 which has a spring loaded choke that must me "clocked" correctly for proper operation. Sounds like yours is wrong and when throttled up the wind sucks it closed because choke in not in sync with choke lever.

It's a 51 and yes it has that spring choke thing. Now that I think of it...when I had the carb off I noticed the choke doesn't open up completely

If it’s a 51 it could very well be that spring. It should not act that bad no matter what the temperature is. It might smoke a little more when it’s cold but it should still rev right up smoothly.
 
(quoted from post at 14:45:36 11/05/17)
I'll have to look at it tomorrow and clean it out. What's the easiest way to.get the intake out?

Is no easy way for that, so it would be best to determine IF the air cleaner is the problem first by removing the pipe from the carb inlet to air cleaner entirely. Now you can check to see if wind passing by choke plate pulls it shut (wrong) or acts to open or unload the spring loaded choke plate (correct assembly). Also worth the time to fix the issue where the choke isn't fully off. Try it now, if problem only returns with connection to air cleaner reinstalled then it's likely the air cleaner needs some work done to it.

Air cleaner will need to be unbolted from frame and stack lowered thru hood if possible, then two long bolts hold the upper intake stack onto the filter body proper. Inside that upper stack is where the wasps will build their mud nests. Hammer shocks to cast iron might do things as well as a garden hose after shock treatment has run out of results. Since I've never done this work myself it just may be that the actual solution involves pulling the hood too.
 
(quoted from post at 22:40:41 11/05/17)
(quoted from post at 14:45:36 11/05/17)
I'll have to look at it tomorrow and clean it out. What's the easiest way to.get the intake out?

Is no easy way for that, so it would be best to determine IF the air cleaner is the problem first by removing the pipe from the carb inlet to air cleaner entirely. Now you can check to see if wind passing by choke plate pulls it shut (wrong) or acts to open or unload the spring loaded choke plate (correct assembly). Also worth the time to fix the issue where the choke isn't fully off. Try it now, if problem only returns with connection to air cleaner reinstalled then it's likely the air cleaner needs some work done to it.

Air cleaner will need to be unbolted from frame and stack lowered thru hood if possible, then two long bolts hold the upper intake stack onto the filter body proper. Inside that upper stack is where the wasps will build their mud nests. Hammer shocks to cast iron might do things as well as a garden hose after shock treatment has run out of results. Since I've never done this work myself it just may be that the actual solution involves pulling the hood too.

I will look into the choke and see how it is operating. What are good settings to set the idle and load screws?
 
Get it good and warmed up and play with the screws. Push the throttle wide open transmission in neutral and slowly screw the load or inside screw in till the engine falters, then screw it back out a quarter turn. This is the initial setting. Pull the throttle back to idle and mess with the idle screw till it idles smooth turning it one click at a time slowly, one click every two seconds or so, once again this is an initial setting. Then put it in road gear out on the road and open her up. If it stumbles turn the load screw out a couple more clicks and try it again. Take your time at it and you will eventually get it right. Seems like the idle setting is tougher to get ‘just right’ than the load setting. It should idle so slow you can count the pops without missing a beat.
 
There is some misinformation on throttle position. Pushing it open "does not open up the carburetor"...all this does is sets the fast idle position of the carburetor....the carburetor doesn't open up till you place a load on it and the load adjusters will not compensate for your problem...the adjusters will allow more fuel and somewhat more power within limitations but when you go on main load the fuel will be delivered on up the nozzle...I've ran the B's on belt under full load and removed the adjusters....I feel the purpose of these is to allow for conservation of fuel for lighter work. as I understand it savy minded thrifty operators would routinely adjust their tractor for job being performed and for peak economy. However you can play with them but I would first see if there is any obstruction in front of the carburetor....best advise given from experience but you decide....
 
(quoted from post at 08:23:23 11/06/17) There is some misinformation on throttle position. Pushing it open "does not open up the carburetor"...all this does is sets the fast idle position of the carburetor....the carburetor doesn't open up till you place a load on it and the load adjusters will not compensate for your problem...the adjusters will allow more fuel and somewhat more power within limitations but when you go on main load the fuel will be delivered on up the nozzle...I've ran the B's on belt under full load and removed the adjusters....I feel the purpose of these is to allow for conservation of fuel for lighter work. as I understand it savy minded thrifty operators would routinely adjust their tractor for job being performed and for peak economy. However you can play with them but I would first see if there is any obstruction in front of the carburetor....best advise given from experience but you decide....

machineryman send me an email if you can- [email protected]
 

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