Idle issues...

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Karl Bader
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Zip Code: 18088
Tractors Owned: 1947 Farmall cub
1952 Farmall cub (some assembly required)
Location: Walnutport, PA

Idle issues...

Postby Karl Bader » Tue Apr 18, 2017 9:08 am

Hey everyone! First off this is my first cub (possibly not my last!) I have a 1947 cub with not a lot of thrills. Just bought it and it has a c3 mower. We bought it to maintain and farm our little 2 acre property. Mowed for the first time and it's the perfect size for us!

Anyway, when I first went to look at it it ran great, this past weekend when we went to load it on the trailer, it idled kind of funny. When you turn the throttle down it would run at the lower RPM and ramp up higher, then go back lower, etc. I'm not sure if I'm looking at a carb issue or a governor issue. the Previous owner did do a carb cleaning and did a basic tune up, he also added in a fuel filter. It starts easily (when I remember to unground the magneto!). Upon a quick outside look at the governor the outer spring does not appear to be stretched or broken. The previous owner had not used this tractor since October and needed a battery jump when I came to see it. He thought maybe bad fuel from sitting for the few months.

Any idea on what I should try or look at? I'm not in a huge rush to fix it as it does run fine and since we just bought our property, we have a lot of work for us to do.

Waif
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Re: Idle issues...

Postby Waif » Tue Apr 18, 2017 10:11 am

Welcome ,and congrats!

Fresh sparkplugs could help , along with clean fresh fuel.

Being it ran great recently I would not suspect the governor.Yet.
Fuel or air related maybe ,before digging into ignition.
Being sure fuel tank is clean and fuel itself ,fuel to and in clean carb can go far in eliminating fuel as an issue. Fresh fuel and seafom are good.

Air leak at or around carb maybe ,but again it ran fine earlier.
Carb jet could have a restriction but until fuel system is clean and filtered before carb ,not a priority.
Research carb jet cleaning and idle tube caution when taking carb apart. Other things like gasket and checking top for being level too.
Valves worth learning about how to check/ adjust.
Clean fuel delivery system from tank through carb . Good spark to sparkplugs at proper time. Air gas mix Zoom,zoom.

Eugene
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Re: Idle issues...

Postby Eugene » Tue Apr 18, 2017 10:37 am

Does the tractor run fine at higher rpms and when mowing?

I would operate the tractor for a while, making notes on problems. As time permits do a complete tune up - basically double checking the tune up conducted by the previous owner.
I have an excuse. CRS.

Jim Becker
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Re: Idle issues...

Postby Jim Becker » Tue Apr 18, 2017 10:44 am

The surging engine speed shouldn't show at low idle, even when you otherwise have a surging problem. At idle, the throttle should be resting against the idle speed adjustment screw. It could be any or several of the things Waif listed. (I'd start with fuel flow and air leaks.) Since the PO just cleaned the carb, an air leak at the carb/manifold gasket is a prime suspect. Once that is taken care of, you could still have a surging problem at higher speed. If so, check the governor to carb linkage adjustment. It should have been readjusted when the carb was installed but may not have been.

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Karl Bader
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Posts: 51
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Zip Code: 18088
Tractors Owned: 1947 Farmall cub
1952 Farmall cub (some assembly required)
Location: Walnutport, PA

Re: Idle issues...

Postby Karl Bader » Thu Apr 20, 2017 10:35 am

Thanks for all the replies! Last night I started her up to move some things around the yard... of course she ran fine, idled down perfectly, and started up so fast I don't think I heard the starter spin... we'll see what happens!

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Karl Bader
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Posts: 51
Joined: Mon Apr 17, 2017 12:45 pm
Zip Code: 18088
Tractors Owned: 1947 Farmall cub
1952 Farmall cub (some assembly required)
Location: Walnutport, PA

Re: Idle issues...

Postby Karl Bader » Mon Apr 24, 2017 8:39 am

The exodus continues! So further research seems like if the choke is not in the perfect sweet spot, this is when the idle issue seems to pop up. I tried grabbing the rod that comes from the governor that was moving slightly back and forth and I could not stop it from doing it's up and down idle. Does this show anything more that I need to dig at?

Thanks,

Karl

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Re: Idle issues...

Postby staninlowerAL » Mon Apr 24, 2017 8:45 am

Partial choke to run good might mean the main jet needs cleaning. Lots of posts about that subject, do a search by using the box at the top right corner of this page.

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Urbish
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Re: Idle issues...

Postby Urbish » Mon Apr 24, 2017 9:06 am

staninlowerAL wrote:Partial choke to run good might mean the main jet needs cleaning. Lots of posts about that subject, do a search by using the box at the top right corner of this page.


:Dito: ....or a vacuum leak. Check condition of carb to manifold gasket and make sure nuts are tight. Could also be the manifold to block gasket but that is unlikely.


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