Spits, Sputters, Dies Under Load

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J3 Driver
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Re: Spits, Sputters, Dies Under Load

Postby J3 Driver » Sun Sep 16, 2018 8:45 am

My sons cub was doing this as well.

Would idle just find even at a high idle. But when you put the old girl under load she would spit, splutter and genrerally not be happy.

Turned out it was the points. And the cap and rotor were corroded too.
15 minutes later and she was as good as new.

A437F3CD-5516-4658-B474-1232D196C8CA.jpeg

Amazing she was still running at all.

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AgTires4295
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Tractors Owned: 1940 Farmall A
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1964 Simplicity Landlord
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Location: La Plata, MD

Re: Spits, Sputters, Dies Under Load

Postby AgTires4295 » Sun Sep 16, 2018 11:37 am

Thanks for the continued support.

I took the fuel bowl assembly completely off, blew it out, put it back together, and installed a large in-line gravity filter that points straight down (to maximize flow with gravity).

Once all back together, I created a vacuum by turning over the engine and it filled wonderfully. It even fired up within 3 seconds of filling just the filter. I tested the fuel flow of the carb by unscrewing the banjo bolt at the reservoir and it poured gas (emptied reservoir) and continuously trickled fuel once completely empty. This rules out fuel flow.

Since I'm doing well with fuel flow (it helps that I can see the fuel pouring into the aftermarket in-line filter now), I thought to myself that maybe I'm not getting enough air. I dropped the oil bath and it was dirty but fine. I cleaned it anyway and put brand new oil in (even though I generally put in filtered used oil...same thing but what the heck).

After putting it all back together, same thing. 30 seconds in, dead.

Just to keep everyone up on the electrical aspects, I've ruled out the coil (sure it gets hot but still throws a bright blue spark at all times). The engine fires right up after sitting for only a couple seconds and will chug again until hitting a heavy load (tall grass).

I've also done the following:

-Replaced points/condenser
-Sanded rotor contacts
-Sanded spark plugs
-Verified strong ignition of spark plugs
-Valve adjustments
-Timed with a timing light
-Cleaned carb (twice)
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1940 Farmall A
1947 Farmall H
1951 Farmall Cub

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Re: Spits, Sputters, Dies Under Load

Postby butchs38 » Sun Sep 16, 2018 12:31 pm

If carb timing points and fuel flow is all good could be bad plugs fouling out under load even if you cleaned them and gaped them. I would throw in at least a new set of plugs and maybe a set of wires cap and rotor.

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AgTires4295
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Tractors Owned: 1940 Farmall A
1947 Farmall H
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1970 Simplicity Broadmoor 728 (x2)
1984 Cub Cadet 782
1964 Simplicity Landlord
2014 Simplicity Broadmoor 23/50
Location: La Plata, MD

Re: Spits, Sputters, Dies Under Load

Postby AgTires4295 » Sun Sep 16, 2018 2:31 pm

Took that advice and not only threw in new plugs but a new battery (thinking what if it didn't have enough amperage while under load). My generator doesn't work so that was a possibility. I just throw it on the charger when I'm done. I'll be rebuilding the generator next.

Once done I was feeling optimistic but there was no imorovement. It stalled at the exact same spots as before. I'm still leaning towards a fuel issue... As if it was running out of fuel at the exact second every time. I just can't imagine what it is. I'll exchange wires, cap, and rotor between tractors to rule that out next but those are all relatively newer items (~2012).
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1940 Farmall A
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1951 Farmall Cub

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Glen
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Re: Spits, Sputters, Dies Under Load

Postby Glen » Sun Sep 16, 2018 5:36 pm

Hi,
Did you do a fuel flow test by removing the plug on the bottom of the IH carburetor, like I wrote in my 2nd post on page 2 of this post.
Also I posted a pic of the small screen at the carb inlet, it has to be clean too. :)

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AgTires4295
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Posts: 196
Joined: Fri Dec 30, 2011 7:36 pm
Zip Code: 20646
Tractors Owned: 1940 Farmall A
1947 Farmall H
1951 Farmall Cub
1970 Cub Cadet 127
1970 Simplicity Broadmoor 728 (x2)
1984 Cub Cadet 782
1964 Simplicity Landlord
2014 Simplicity Broadmoor 23/50
Location: La Plata, MD

Re: Spits, Sputters, Dies Under Load

Postby AgTires4295 » Sun Sep 16, 2018 5:52 pm

Affirm. I have fuel flowing rapidly out of the plug (as I was hoping for).

I deleted the screen at the carb inlet a few years back.
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1940 Farmall A
1947 Farmall H
1951 Farmall Cub

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Denny Clayton
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Re: Spits, Sputters, Dies Under Load

Postby Denny Clayton » Mon Sep 17, 2018 10:36 am

AgTires4295 wrote:Thanks for the continued support.

I took the fuel bowl assembly completely off, blew it out, put it back together, and installed a large in-line gravity filter that points straight down (to maximize flow with gravity).

Once all back together, I created a vacuum by turning over the engine and it filled wonderfully. It even fired up within 3 seconds of filling just the filter. I tested the fuel flow of the carb by unscrewing the banjo bolt at the reservoir and it poured gas (emptied reservoir) and continuously trickled fuel once completely empty. This rules out fuel flow.

Since I'm doing well with fuel flow (it helps that I can see the fuel pouring into the aftermarket in-line filter now), I thought to myself that maybe I'm not getting enough air. I dropped the oil bath and it was dirty but fine. I cleaned it anyway and put brand new oil in (even though I generally put in filtered used oil...same thing but what the heck).

After putting it all back together, same thing. 30 seconds in, dead.

Just to keep everyone up on the electrical aspects, I've ruled out the coil (sure it gets hot but still throws a bright blue spark at all times). The engine fires right up after sitting for only a couple seconds and will chug again until hitting a heavy load (tall grass).

I've also done the following:

-Replaced points/condenser
-Sanded rotor contacts
-Sanded spark plugs
-Verified strong ignition of spark plugs
-Valve adjustments
-Timed with a timing light
-Cleaned carb (twice)

The carb bowl should maintain a steady stream once it empties. It should NOT be a trickle. A trickle to me says a fuel restriction somewhere up the line. Since the engine fires right up after a couple seconds, I think you still have a restriction.
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Re: Spits, Sputters, Dies Under Load

Postby Crimson Tim » Mon Sep 17, 2018 9:54 pm

:Dito:

My thought as well when I saw that word. I fought a battle like this a while back. I thought I had enough fuel flow, but I was wrong. It takes a surprisingly strong stream of fuel to keep a Cub happy. I would say a good strong stream larger than a pencil. Way more than I would ever have thought to use the word “trickle” for.

In my case, it was rust in the tank causing problems. I know it’s frustrating, because you think you’ve cleaned everything already. And maybe you have... and it’s just crudded right back up again. Or maybe there’s still some nook or cranny that you’ve still missed. But it sure still sounds like a fuel flow problem to me.

There have been a couple no-start threads lately, and I am having trouble keeping the different symptoms for the different people straight.
Does yours run a bit longer/better if you give it some/a lot of choke? If so, fuel issue.
How about starting fluid? Can you keep it running by giving it little spritzes of starting fluid through the carb air intake? If so, it’s not getting fuel, but air, spark and timing are ok.
Does the carb seal well to the intake manifold and the two halves of the carb seal well together? If not, you’ll get too much air so will look like a fuel issue. Spritz a little starting fluid near the outside of these gaskets just as it is starting to die. If it suddenly takes off and runs better, you’ve got a vacuum leak at one of those gaskets. A warped top is common.
When you’ve had the carb apart, have you checked the float condition, height and drop?
Is there any way you could have gotten a mismatched needle and seat in the carb? Or a wrong orifice size somewhere? I have read that there were a couple different parts over the years, and as long as they were all matched to each other you’d be fine.

It’s hard to say more than that, not being there to witness this first hand. Maybe posting a video would help. A lot of the members have amazingly keen eyes and ears for trouble and may be able to pick up a clue that way.

One last suggestion would be to hook up a pony tank with a new line to the carb of at least 5/16”. That will remove the tank, sediment bowl, existing fuel line and filter from the equation. I think you said you took the filter and sediment bowl out already, but you get what I’m after.
Do you have access to another carb off of a running tractor? Swap that in, and that will also help you troubleshoot whether that makes a difference or not.

Good luck. These little tractors can seem fussy when they are feeling sulky, but they are rewarding once you get them sorted. Get them happy, and there’s nothing they love more than to go to work! Keep at it. You’ll get it.

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Re: Spits, Sputters, Dies Under Load

Postby outdoors4evr » Tue Sep 18, 2018 9:30 am

There has been a lot of focus on this thread around electrical and fuel delivery. I think it is worth noting that good airflow is also required for full throttle operation. Make sure that your air cleaner is providing good clean air to your engine. (Might want to disconnect the air cleaner from the carb for a test) and also verify that the exhaust is clear and unobstructed. A partially blocked intake or exhaust may run well at an idle, but causes issues at higher throttle settings.

Ya never know how many nuts a squirrel can stuff in an exhaust pipe. Mice also like to contribute a new nest to an open exhaust pipe.
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