No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

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jaybee19
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No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby jaybee19 » Wed Apr 01, 2020 9:18 pm

Okay, so my Cubbie that I’m trying to get going is a ‘49. It started out puffing along and cutting grass like a champ and did so for maybe ninety minutes tops, but now it’ll sit around and idle fine, but try to climb a hill or even place a load on a slight incline, it sputters, surges, and conks out pretty shortly. It started out with pretty responsive throttle, although it would RPM hunt a good bit. I’ve tried to inspect and have twice adjusted the gov/throttle linkage, but the issue I’m seeing is that it works whenever the tractor’s off but does nothing with the tractor running unless you slam it past the notches, and then sometimes it revs up like crazy, sometimes it doesn’t do anything. It’ll do a little more cold, but as it warms up, it quickly becomes stubborn. Either way, something's fishy there, and my guess is something inside the unit because the actuator spring and the linkages check out.

I feel that I have a second problem with the float height because it just won’t climb a hill nose up without sputtering and quickly dying out. Sometimes it’ll idle nose up and sometimes it’ll start and run for a few seconds and stall again. I’ve seldom, if ever, had an issue nosedown. In fact, I’ve climbed a steep hill with it in reverse just to see what happened, and it did fine. I’ve got good spark, point gap set to spec, timing is good, input voltage is nominal, but the mark bounces around like a car with a sloppy timing chain would. I’m confident the ignition system is good to go. I did clean the carb to perfection, and it’s getting clean ethanol free 87, but I only put in a new main jet/nylon washer and float out of a parts carb because the old ones were damaged. I should have been mindful of float height, but I was preoccupied with being careful because the only kits you can get locally are TSC (known junk) and Napa (unsure of quality), plus both are micro-kits. I didn’t want to break anything that would warrant buying a Steiner kit and sitting around waiting for it. I don’t know if it’s relevant, but it does better starting with little or no choke, and it’ll die out if you reengage the choke when warm.

Bottom line, I do a good bit of auto work so this is simpler than what I’m used to, so much so that I feel like I’m missing picayune details rather than facing a huge disaster. I need to see about the carb, but I don’t know enough about how the governor works that I can deduce how much of the problem it’s causing. I tried to find comparable situations to mine via search to no avail so any help would be greatly appreciated.

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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby staninlowerAL » Wed Apr 01, 2020 9:33 pm

The lever where the governor spring attaches MUST work without any restriction. Have you checked all the linkages to see if they are restricted in any way? Also sounds like you have a fuel restriction somewhere. There's supposed to be a filter screen in the fuel shutoff valve sediment bowl and one in the inlet of the carb where the fuel line attaches. Could be debris/trash/rust in the tank. The main jet has very small orifices and it does not take much to plug it up.

jaybee19
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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby jaybee19 » Wed Apr 01, 2020 10:53 pm

Sorry, should have specified about the fuel system a little better. I swished the tank several times with gasoline and cleaned all the dirt, rust, and varnish out of the sediment bowl and screen. It also has a new see-through inline filter, which it had one before. I’m assuming it was done in lieu of an inlet screen because it doesn’t have one, and instead of a flare fitting and steel hose, it has a hardware store style barb fitting and a rubber fuel hose goes over that. The sediment bowl has some particles on the bottom, but the filter is clear as day and fills up adequately. I’ve seen posts of others saying that some tractors do fine with an inline filter, and some don’t. It’s just one of those things that they’re collectively fickle about. Maybe it’d do better without one, and I’m certainly open to trying. I will say that the bowl gasket is pretty well shot on my carb. The carb is dry when it’s running, but if you leave it sitting it’ll get moist around the seal and drip gas from the plug in the throat. If CASE-IH wasn’t 70 minutes away, I would have at least thrown a new bowl gasket on, but I’m gonna pull the carb and see if the NAPA kit’s gaskets help things out. I was trying to get this back together very hurriedly, and I’m not usually so cavalier with fixing things, but the grass is getting tall, and I was hoping to make the first cutting and then I could workshop whatever bugs I encountered.

As far as the linkages go, the input side of the governor circuit is great; there’s no binding in that rod to speak of. I don’t have a second tractor to refer to, but I would like to see the throttle side lever move smoother and more consistently rather than being choppy if that makes sense. I adjusted it so the butterfly is fully closed at the rearmost notch, but when the tractor’s off, the output side doesn’t move very much until the lever’s at around 12 o’clock, give or take. If the tractor’s warm, it won’t do anything until close to the 9 o’clock position. I’m gonna pull the cowl again, look closer, and see if I can see something that I might have missed, but what gets me is that it does little to nothing at operating temp.

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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby Bob McCarty » Wed Apr 01, 2020 11:07 pm

Check and make sure that the inline filter is for a gravity feed fuel system. If it's for a fuel pump system, that's at least part of the problem. There were a variety of main jets. You might want to put the old one back in and see if that makes any difference. Clean the orifice with a small copper wire or blow it out well with carb cleaner.
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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby Jim Becker » Wed Apr 01, 2020 11:14 pm

jaybee19 wrote:. . .
I adjusted it so the butterfly is fully closed at the rearmost notch, . . .

You are doing this adjustment at the wrong end of the scale. To adjust the linkage from the governor to the carburetor:
- engine off
- unpin linkage at the front end
- push control lever forward
- hold linkage rod back (fully open throttle)
- adjust length of link so the pin will slide in.

This may not solve your problem but should be a step in the right direction.

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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby outdoors4evr » Thu Apr 02, 2020 5:47 am

The sputtering sounds like an acceleration issue (moving from a low RPM to a higher RPM). This is usually attributed to the idle air inlet adjustment on the top of the carb. See Link:
http://www.tmtractor.com/new/fl/125fp.htm

This is an idle air inlet so turning it in (clockwise) will allow less air in so it will allow more fuel in and richen the mixture. Turning it out (counterclockwise) lets more air in and less fuel to lean the mixture. Small adjustment changes make big impact. Make changes in 1/4 to 1/8 turn changes till you get it close, then smaller.
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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby Gary Dotson » Thu Apr 02, 2020 7:25 am

I agree with Jim! Adjust the linkage rod (governor rock shaft to carb.) according to his instructions then move on toward finding the problem. That linkage adjustment is a set-up adjustment, not a tuning adjustment.
One question that may sound silly: You mentioned that it would not climb a hill going forward but would in reverse, How much fuel is in the tank? The fuel delivers at the front of the tank so low fuel level can cause this symptom.

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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby Eugene » Thu Apr 02, 2020 7:22 pm

jaybee19 wrote:I’ve got good spark, point gap set to spec, timing is good, input voltage is nominal, but the mark bounces around like a car with a sloppy timing chain would.
Couple of thoughts; condenser, or coil breaking down. Check to see that the rotor is pointed directly at the distributor plug tower when engine is set on TDC #1 cylinder. Condition of the rotor and distributor cap. Spark plug condition.

Surging is usually fuel related.
I have an excuse. CRS.

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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby jaybee19 » Thu Apr 02, 2020 11:57 pm

A lot to unpack and report on. I set up the throttle adjustment as it was stated above. What I’m seeing now, also with the cowl removed, is that the spring is not catching the hook in the horizontal rod until the throttle lever’s at about 12 o’clock, then it’ll start to move. That’s with the tractor off. Tractor on, same starting point, but the the throttle lever will get rigged on just a little bit and fall back down to idle. The output side isn’t moving at a 1:1 ratio with the input side, rather there’s a delay where the output side tries to “catch up” with a quick stroke of that actuator lever. What’s the adjustment screw there for? I’ll attach a pic, but it’s vertically oriented and really close to the generator pulley/belt.

As far as my fuel situation goes, good and bad news. The top side of the carb is warped pretty good. I don’t think a regular seal would be thick enough to get it, but it looks like someone made a homemade one, and there’s no vacuum leaking so I left it alone for now. I was going to use a good top from a different carb, but while cleaning it up right before I was to reassemble, the idle tube broke so that was that. My float height and drop were wrong so I fixed both. I think that’s gonna fix my leaking throat plug while sitting around. I also found a sludge/rust impaction in the sediment bowl inlet. I thought I cleaned the tank well, but I guess not well enough. I suppose that’ll help a lot once I reclean and reassemble. I checked gravity fuel flow with and without the filter, and the streams were the same. Although, that was before the goo was extracted from the valve. I’ll also attachable couple of videos where I tried to capture the disparity of the throttle input and output with the engine off. It doesn’t even seem that bad on a cold engine, but it can only try when it’s running for some reason.

Most ignition parts are new. Cap, rotor, points, condenser, plugs, and wires. Coil passed that ground out test where you hook the plug directly to it and make it spark, plus both primary/secondary leg resistance readings were within spec via my DVM. Spark is bluish white, painful to the touch unfortunately. And yeah, I made sure that the rotor was in sync with the #1 dist. pin. I had to readjust point gap (too hot) and my timing went from dead on to a hair off so I’ll give it a nudge as soon as I can. I washed the tank out so I’ll leave it alone till tomorrow afternoon. No rust floating around, more like dust bunnies and misc. trash from sitting in a dirty barn with no cap for several years. I really thought I got most of the stuff when I swished several gallons of gasoline in it, but I guess not. I used water and was far more aggressive this time.

https://youtu.be/IcTlnJAwitI

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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby Don McCombs » Fri Apr 03, 2020 6:46 am

With the engine off, lube all moving points in the entire throttle/governor linkages. Work the system back and forth numerous times. Then try it with the engine running. Report back on any changes.

If you had debris in the tank, the fuel inlet screen on the carburetor may be partially blocked. Check and clean that, also.
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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby Bob McCarty » Fri Apr 03, 2020 9:27 am

The calibrated orifice of the idle tube is in the threaded end in the top. You can change tops without putting in a new idle tube and be okay. Where the rockshaft across the front of the engine inserts into the governor arm, there is a keyway that often gets wallered out. Disconnect the arm on the carb side and see if you have a lot of play in the rockshaft. If so, there are a couple of "how to's" on fixing that. One uses shims, the other uses JB Weld to "glue" the arm and keyway to the lever. That's what I'm guessing from the video.

Edit: The hole that the spring goes through can also be wallered out and contribute to the lag or slop between the two sides; also fixable.
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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby Jim Becker » Fri Apr 03, 2020 12:14 pm

There is one more thing to check that your video brought to mind. The linkage from the governor to the carburetor needs to be able to move smoothly with no binding or rubbing anywhere throughout its range of motion. After you make the checks Bob described and get the linkage tightened up as needed, make sure it moves smoothly through the full range.

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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby Glen » Fri Apr 03, 2020 6:05 pm

Hi,
The adjustment on top of the governor that you asked about is the high speed limit adjustment.

A 1949 Cub engine should run at 1800 RPM maximum speed.
The slow idle speed is 500 RPM.
Check the speed with an automotive test tachometer.
They have said on here that a tach with a pointer and dial works better for a Cub.

Below are pics from TM Tractor of the governor.
The 1st pic shows the high speed adjustment bolt.

Oil where the cotter key is in the 2nd pic, and work it into the pivot, they commonly get tight there from no lube. :)
Attachments
Cub gov 7.jpg
Cub gov 3.jpg

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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby jaybee19 » Fri Apr 03, 2020 10:28 pm

Fuel system cleaned up, and I think it’s good to go this time. My carb doesn’t leak gas anymore, and no sign of it leaking vacuum so I’ll let sleeping dogs lie with that one. I drove it around, albeit with no more than a hair above idle throttle at my disposal, and it didn’t sputter, surge, or anything. It ran pretty consistently, hills and all.

I lubed all the moving parts as best I could. Even though it’s kinda sloppy, I do have the full range of travel getting to the throttle arm with it off. No difference while running. Watch what it does with the tractor running while I have it “floored” and held there. Something had to have broken because it had pretty responsive throttle when I first started using it, it was just very sensitive and finicky.

https://youtu.be/DoqlByzu0EI

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Re: No Throttle Adv. w/ Tractor Running and Won’t Climb Hills

Postby Jim Becker » Fri Apr 03, 2020 10:52 pm

Replace that cotter pin with a real 3/16 pin.


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