Engine hunts and carb won't adjust

Farmall Cub Forum -- Questions and answers to all of your Cub related issues.

Moderator: Team Cub

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.

Engine hunts and carb won't adjust

Postby 169Cub » Mon Nov 05, 2012 8:19 pm

I did a search about engine hunting and read that if the choke is pulled slightly and the engine smooths out that the carb needs to be adjusted. So, I tried that and when the choke is out a tad the engine smooths out. So I adjust the carb and there is no difference... I screwed the adjusting screw all the way in and set it at 1.5 turns and there was no difference. Then I tried 2 turns and still the same. Then I just let the engine run and ran the screw all the way in and the engine never died. With my Cub Cadets this would have stopped the engine. No matter where the set screw is placed, I still get the same hunting unless I slightly pull the choke out... I am stumped.
Lovin' IH for over a decade.
169Cub
Cub Star
Cub Star
 
Posts: 74
Joined: Mon Jun 25, 2012 4:23 pm
Zip Code: 54904
eBay ID: jsdnar
Tractors Owned: Original Cub Cadet
100
123
126
129
169 x2
1650
782
1957 Farmall Cub
John Deere 3120

Re: Engine hunts and carb won't adjust

Postby Lurker Carl » Mon Nov 05, 2012 8:24 pm

The main jet has gunk in it. It is the brass hex "nut" on the bottom side of the carburetor bowl.
"Chance favors the prepared mind."
- Louis Pasteur

"In character, in manners, in style, in all things, the supreme excellence is simplicity."
- Henry Wadsworth Longfellow
User avatar
Lurker Carl
Team Cub Mentor
Team Cub Mentor
 
Posts: 3939
Joined: Mon Feb 03, 2003 9:54 am
Location: PA, Todd
Zip Code: 16685
Circle of Safety Award
Circle of Safety: Y

Re: Engine hunts and carb won't adjust

Postby ricky racer » Mon Nov 05, 2012 9:03 pm

:Dito:

I just went through the same thing here.
1929 Farmall Regular
1935 John Deere B
1937 John Deere A
1941 John Deere H
1952 John Deere B
1953 Farmall Cub
User avatar
ricky racer
5+ Years
5+ Years
 
Posts: 2793
Joined: Wed Sep 12, 2007 8:40 pm
Location: Niles / Buchanan, Michigan
Zip Code: 49120
Circle of Safety Award
Circle of Safety: Y

Re: Engine hunts and carb won't adjust

Postby Bus Driver » Mon Nov 05, 2012 9:28 pm

Lurker Carl wrote:The main jet has gunk in it. It is the brass hex "nut" on the bottom side of the carburetor bowl.


Not the bottom, it is on the side. The only 3/8 hex on the carburetor. A 3/8 box end wrench is the best as it fits only the jet on the carburetor.
Luck favors those who are prepared
User avatar
Bus Driver
Team Cub Mentor
Team Cub Mentor
 
Posts: 2650
Joined: Sat Feb 11, 2006 5:26 pm
Location: NC

Re: Engine hunts and carb won't adjust

Postby Matt Kirsch » Tue Nov 06, 2012 11:37 am

AFAIK, the adjustment screw only controls the idle air circuit. Most tractors will still get enough air through the regular intake to run at idle, and the needle has no effect at anything but an idle.

Cubs with OEM IH carbs do not have any "high speed" adjustment for the carburetor mixture. High speed adjustment is achieved by resetting the float height slightly higher or lower as determined by the way the tractor is running. Normally it is not necessary.

Is your governor rod timed right to the carburetor?
Matt Kirsch
10+ Years
10+ Years
 
Posts: 3338
Joined: Tue Jun 08, 2004 3:04 pm
Location: Rochester, NY
Zip Code: 14559
Circle of Safety Award
Circle of Safety: Y

Re: Engine hunts and carb won't adjust

Postby Eugene » Tue Nov 06, 2012 12:29 pm

Engine hunting is usually fuel flow related.

Does the engine start hunting immediately upon start up? If so the problem is probably carburetor related. If the problem shows up after a minute or so the problem is fuel flow.

Remove the plug from the bottom of the carburetor and check the fuel flow for 30 seconds or a bit longer.

Have you removed the carburetor? There is suppose to be a screen at the inlet to block debris.

Read your previous posts. Engine runs. Have you conducted a 100% tune up including compression tests?
I have an excuse. CRS.
Eugene
Team Cub Mentor
Team Cub Mentor
 
Posts: 12499
Joined: Fri Jul 02, 2004 9:52 pm
Location: Mo. Linn
Zip Code: 65051
Circle of Safety Award
Circle of Safety: Y

Re: Engine hunts and carb won't adjust

Postby 169Cub » Tue Nov 06, 2012 3:32 pm

The problem is resolved. I took the "plug" out the side of the carb and it was full of gunk! I mean, the oriface that runs through the center of the shaft was clogged and the center tube portion was clogged too. I dropped it in some carb cleaner, cleaned it out and ran air through it. I took some carburator cleaner and sprayed it in the idle adjusting screw and cleaned that too. Then I put it back together and fired her up. She ran better, with no hunting, but the engine sounded weak and sputtered. I ran her around the field and up and down the road with the deck on to create more load for the engine and after about 10 minutes or so she stopped sputtering and ran smooth. So thank you for the pointers. Now I also know how to adjust the high speed portion by adjusting the float. I didn't know that either. I appreciate all your help and suggestions. :D
Lovin' IH for over a decade.
169Cub
Cub Star
Cub Star
 
Posts: 74
Joined: Mon Jun 25, 2012 4:23 pm
Zip Code: 54904
eBay ID: jsdnar
Tractors Owned: Original Cub Cadet
100
123
126
129
169 x2
1650
782
1957 Farmall Cub
John Deere 3120

Re: Engine hunts and carb won't adjust

Postby Rudi » Tue Nov 06, 2012 5:04 pm

And that was the brass hex "nut" that Carl was referring to. Suggest you read his Lurker Carl's Cub Carb Fixes, it is a great set of articles.
Confusion breeds Discussion which breeds Knowledge which breeds Confidence which breeds Friendship

User avatar
Rudi
Team Cub
Team Cub
 
Posts: 28467
Joined: Sun Feb 02, 2003 8:37 pm
Location: NB Dieppe, Canada
Zip Code: E1A7J3
eBay ID: ve9rhs
Skype Name: R.H. "Rudi" Saueracker, SSM
Tractors Owned: 1947 Cub "Granny"
1948 Cub "Ellie-Mae"
1951 Cub "Jethro"
Dad's Putt-Putt
IH 129 CC
Circle of Safety Award
Circle of Safety: Y
Twitter ID: Rudi Saueracker, SSM

Re: Engine hunts and carb won't adjust

Postby Boss Hog » Tue Nov 06, 2012 6:12 pm

Bus Driver wrote:
Lurker Carl wrote:The main jet has gunk in it. It is the brass hex "nut" on the bottom side of the carburetor bowl.


Not the bottom, it is on the side. The only 3/8 hex on the carburetor. A 3/8 box end wrench is the best as it fits only the jet on the carburetor.




Carl said the bottom side of the Carb.
IN GOD WE TRUST
All others pay cash
Boss Hog
Power corrupts; absolute power corrupts absolutely byJohn Emerich Edward Dalberg
User avatar
Boss Hog
Cub Pro
Cub Pro
 
Posts: 9802
Joined: Mon Oct 24, 2005 8:35 pm
Location: VA. Randolph
Zip Code: 23962
eBay ID: dmb2613
Circle of Safety Award
Circle of Safety: Y

Re: Engine hunts and carb won't adjust

Postby Bus Driver » Thu Nov 08, 2012 8:19 am

It is fortunate that the carburetor cleaner did the job in this instance. Fuel gum must have been the problem. And some of it apparently caused problems for a few additional minutes. Additional gum could have been in the bowl of the carburetor. In normal operation, the only way fuel leaves the carburetor bowl is by passing through the jet.
Frequently rust flakes will clog the jet and only mechanical cleaning (with a smooth fine wire) will dislodge those. Carburetor cleaner does not dissolve rust flakes. I know of no substance that will dissolve rust while leaving brass (the jet) undamaged.
Often I carry a 3/8 wrench and smooth tip cleaners when I am using the Cub. Occasionally they are needed.
Luck favors those who are prepared
User avatar
Bus Driver
Team Cub Mentor
Team Cub Mentor
 
Posts: 2650
Joined: Sat Feb 11, 2006 5:26 pm
Location: NC


Return to Farmall Cub

Who is online

Users browsing this forum: Ironlegs, outdoors4evr, shyntempt and 11 guests