Fuel/air problem

The Cub Club -- Questions and answers to all of your Cub related issues.
Forum rules
Notice: For sale and wanted posts are not allowed in this forum. Please use our free classifieds or one of our site sponsors for your tractor and parts needs.
Torson
Posts: 4
Joined: Fri Mar 13, 2020 10:05 am
Zip Code: 02030

Fuel/air problem

Postby Torson » Fri Mar 13, 2020 10:12 am

I need help diagnosing a problem. My 1948 cub sometimes only runs if I have the choke partially open. It stalls if I open or close it all the way. What could be causing this? (I also notice a puffing sound coming from the engine every 2nd or 4th stroke?) Thanks for any advice.

User avatar
Barnyard
Team Cub
Team Cub
Posts: 23472
Joined: Tue Aug 07, 2007 3:39 pm
Zip Code: 45030
Tractors Owned: At This Time
40 Farmall Cubs (Round Hood)
2 Farmall Cub (Square Hood)
2 IH Cubs (Square Hood)
5 Lo-Boys (Round Hood)
2 Lo-Boys (Square Hood)
2 Farmall 404's
1 Farmall H
1 Ferguson 20
1 Cub Cadet 125
1 Kubota B-7100
Circle of Safety: Y
Location: OH, New Haven (Hamilton County)

Re: Fuel/air problem

Postby Barnyard » Fri Mar 13, 2020 10:24 am

Remove the main jet on the side of the carb and clean the orifice with a small copper wire and spray through it wit carb cleaner.
There are two ways to get enough Cubs. One is to continue to accumulate more and more. The other is to desire less.

Circle of Safety

Torson
Posts: 4
Joined: Fri Mar 13, 2020 10:05 am
Zip Code: 02030

Re: Fuel/air problem

Postby Torson » Fri Mar 13, 2020 2:19 pm

Thank you. I decided to clean the carburetor while I was at it. Now I have to wait for a manifold gasket before I can see if the problem is solved. The old gasket tore in half at separation.

Sadcub
Posts: 37
Joined: Mon Feb 03, 2020 12:21 am
Zip Code: 76066
Tractors Owned: 1948 CUB
1948 CUB
1984 FORD 3910
Location: Millsap, TX

Re: Fuel/air problem

Postby Sadcub » Fri Mar 13, 2020 3:25 pm

I have had a similar problem. You are too lean and that is why the need for choke. Barnyard nailed it. My main jet was clogged, even though I took everything apart and cleaned it. The orifice is so small it takes a wire to get it cleaned out.

User avatar
Barnyard
Team Cub
Team Cub
Posts: 23472
Joined: Tue Aug 07, 2007 3:39 pm
Zip Code: 45030
Tractors Owned: At This Time
40 Farmall Cubs (Round Hood)
2 Farmall Cub (Square Hood)
2 IH Cubs (Square Hood)
5 Lo-Boys (Round Hood)
2 Lo-Boys (Square Hood)
2 Farmall 404's
1 Farmall H
1 Ferguson 20
1 Cub Cadet 125
1 Kubota B-7100
Circle of Safety: Y
Location: OH, New Haven (Hamilton County)

Re: Fuel/air problem

Postby Barnyard » Fri Mar 13, 2020 3:30 pm

Image

Image
There are two ways to get enough Cubs. One is to continue to accumulate more and more. The other is to desire less.

Circle of Safety

Torson
Posts: 4
Joined: Fri Mar 13, 2020 10:05 am
Zip Code: 02030

Re: Fuel/air problem

Postby Torson » Wed Mar 18, 2020 11:49 am

Thanks very much for the help. I finally got the gasket, reattached the cleaned carburetor, and the tractor is running well. However, discovered I have a bad oil leak. I think it is coming through the seem between the clutch housing and the half moon shaped plate that is bolted to it. The plate is bent in two places. Any thoughts? Thanks.

Bob McCarty
Team Cub
Team Cub
Posts: 11112
Joined: Tue May 25, 2004 8:02 pm
Zip Code: 80501
Tractors Owned: Cubs, MH Pony, Shaw, Allis G, 1934 Silver King, JD LA and LI, Gibson D, David Bradley Tri-Trac
Circle of Safety: Y
Location: CO, Longmont

Re: Fuel/air problem

Postby Bob McCarty » Wed Mar 18, 2020 12:05 pm

Sounds like your rear main engine seal is leaking. The fix is to split the tractor and replace the seal. The replacement seals that are sold only fit a later retainer. You'll need to have the old retainer machined for a larger seal. Tim Talleur (forum name tst) does that. He may have a post on the Vine (classified) sub-forum.

Edit: viewtopic.php?f=223&t=106799
"We don't need to think more,
we need to think differently."
-Albert Einstein

User avatar
Glen
10+ Years
10+ Years
Posts: 5352
Joined: Mon Mar 19, 2012 7:33 pm
Zip Code: 00000
Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
Circle of Safety: Y
Location: Wa.

Re: Fuel/air problem

Postby Glen » Wed Mar 18, 2020 7:40 pm

Hi,
Below is the Cub and LoBoy service manual. I suggest you read section 1, the engine section before splitting the Cub to replace the engine rear seal.
Section 4 has info about splitting a Cub. :)

http://farmallcub.com/rudi_cub/www.clea ... index.html

There is info in the How To section on here about making splitting stands, at least one post I saw the stand has a wheel at the bottom.

Be sure to use wooden wedges at the front axle pivot before splitting a Cub or LoBoy, they are heavier on the left side and can tip over without wedges. You will need to make the wedges.
Hammer them in tight, and check them some during the work, to be sure they don't loosen or fall out.
Below is a pic from Dale Finch.
Attachments
Cub wedges 2.jpg


  • Similar Topics
    Replies
    Views
    Last post

Return to “Farmall Cub”

Who is online

Users browsing this forum: No registered users and 2 guests