Carb issues....surging, flooding, dying, won't start

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Jim Becker
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Re: Carb issues....surging, flooding, dying, won't start

Postby Jim Becker » Mon Mar 27, 2017 4:27 pm

noisyone wrote: . . . even at full throttle, the carb throttle plate only is only about half way open. Is that normal, or should it be opening all the way to the max?

Engine running or not? If not running, carb should be wide open. If running it should only be part way.

I notice your choke isn't fully open. The engine should be warm enough to open the choke before dealing with this.

Have you pulled the drain plug on the carburetor and opened the fuel valve to make sure you have a good solid and continuous stream of fuel?

Have you checked the shaft that comes out of the left side of the governor for a good fit at the inner end? If it is loose, surging will be difficult to eliminate. There have been previous discussions of how to fix that if it is a problem.

Earlier in this thread, there was discussion of adjusting the linkage between the governor and carb. Have you done that? It will have to be redone if you have to fix the problem in my previous point.

Once all the above is in order, make sure the governor to carb linkage moves freely without any binding, rubbing on other parts etc.

If it still surges after all the above, there is an adjustable bumper spring on the front side of the governor. You can turn that in a little (like 1/2 turn) at a time to eliminate the surging. You may have to remove it completely to inspect and clean it before it will work properly. This is very close to the fan, so shut the engine off to make adjustments.

By the way, your tie rods are not properly installed. They should cross each other at the center.

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Re: Carb issues....surging, flooding, dying, won't start

Postby noisyone » Mon Mar 27, 2017 4:55 pm

Hmmm, perhaps the video isn't clear. The choke is fully open. I've even removed the air intake tube and looked inside to verify it's fully open.

Yes, as a follow up, the throttle plate opens fully when the engine is off, but opens partially when the engine is running. I wasn't sure if that is normal or not but it sounds like it is.

I have previously checked the fuel flow and it was good. I could recheck that.

It does appear to have some "slop" or looseness in the shaft that comes out of the governor. Perhaps that is my issue?

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Re: Carb issues....surging, flooding, dying, won't start

Postby Waif » Mon Mar 27, 2017 6:33 pm

J.B. is referring to the choke plate actuator(?) . If you had no choke rod from operator station to carb ,you would operate the choke ( and can with one equipped with a rod to operator station as well) by turning the rectangular piece/ (plate with a hole in yours) either down,( parallel to engine) to choke or up with your fingers for full open, or a setting in between.
In your video ,the plate is midway,rather than full open and your engine is not " cold"That's what we're seeing. But why is it not opened?
Not all ,but many cubs when dialed in the choke can be bumped full open after it starts ..in warm weather right away .

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Re: Carb issues....surging, flooding, dying, won't start

Postby Glen » Mon Mar 27, 2017 6:57 pm

Hi,
Here is a page from a Cub LoBoy owner's manual showing what Jim said above about the tie rods in the center. :)

http://farmallcub.com/rudi_cub/www.clea ... age-02.jpg

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Re: Carb issues....surging, flooding, dying, won't start

Postby Eugene » Mon Mar 27, 2017 7:25 pm

Zip Code 66111, Kansas City area. There are several Cub Fests within a couple hours drive. Why not trailer your Cub to a Cub Fest? Have the guys look it over and help straighten out some problems.
I have an excuse. CRS.

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Re: Carb issues....surging, flooding, dying, won't start

Postby staninlowerAL » Mon Mar 27, 2017 8:34 pm

Glen wrote:Hi,
Here is a page from a Cub LoBoy owner's manual showing what Jim said above about the tie rods in the center. :)

http://farmallcub.com/rudi_cub/www.clea ... age-02.jpg

Here's a close up picture of the steering rods:
steering tie rods.JPG
This change was at LoBoy tractor SN 4802. (See part reference number 31.) Stan
Attachments
steering arm parts list.JPG

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Re: Carb issues....surging, flooding, dying, won't start

Postby Crimson Tim » Mon Mar 27, 2017 10:58 pm

You have mentioned that there is some slop in the linkage from governor to carb. It is my understanding that there should be virtually no slop there, or the engine speed responses will be very erratic. Somebody recently (was that you, Dale?) was rebuilding that linkage, where a previous owner had welded a shaft connection at the governor to try to fix a seriously wallowed out keyway. That probably worked, until the weld gave out. Long story short, if you have a lot of slop there, I think you will not get your engine speed issues completely resolved until you address that. All the linkage connections bear examination, but that keyway in particular would be interesting to check out.

You may have other issues in addition.

What I'm curious about is your fan belt. I've watched the latter half of your video a half dozen times now, and it looks to me like the fan belt moves fore and aft in sync with the movement of the transverse governor shaft. Is it really doing that??? :shock:
The bottom of the fan belt goes around a pulley connected directly to the engine crankshaft. That shouldn't be moving. It looks stable throughout the video, so that is good.
The top of the fan belt goes around the fan pulley. That shouldn't be moving either, but it looks like it is. So I'm thinking something is either loose around the fan mount OR is the governor shaft somehow rubbing on the fan belt in some positions? The latter ought to mess with your engine speeds.

That makes me want to run out and try revving up mine to see if it looks the same, and if it does, what causes that illusion. It's after midnight though, and it's parked out front. That might make the neighbors talk more than they do already. :lol:

Good luck.

Jim Becker
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Re: Carb issues....surging, flooding, dying, won't start

Postby Jim Becker » Tue Mar 28, 2017 12:44 am

Crimson Tim wrote:. . . What I'm curious about is your fan belt. I've watched the latter half of your video a half dozen times now, and it looks to me like the fan belt moves fore and aft in sync with the movement of the transverse governor shaft. Is it really doing that??? :shock: . . .

I think the fan belt is loose. As the engine speed reacts to the governor, the slack moves from one half of the belt to the other. The synchronized side movement of both sides of the belt gives the illusion of fore-aft movement.

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Re: Carb issues....surging, flooding, dying, won't start

Postby Crimson Tim » Tue Mar 28, 2017 1:04 am

I was hoping that was all that was going on, but sure looked odd from that angle!

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Re: Carb issues....surging, flooding, dying, won't start

Postby noisyone » Tue Mar 28, 2017 7:26 pm

Thank you all for this recent advice. I will be working on it tomorrow and looking into these suggestions about the governor linkage, as well as the front tie rods.

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Carb issues....surging, flooding, dying, won't start - FIXED

Postby noisyone » Mon Apr 24, 2017 9:55 pm

Problem is fixed and tractor is running great. The problem ended up being the adjustment bolt on the side of the governor. I turned it in several turns and there is no more revving up and down under load. Thanks for all the help. Now that it's running...I've got lots of leaky gaskets to replace.


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