Lean carb on 1800 Oliver

Vern A · Nov 7, 2016

I recently bought a 1800 Oliver. The other person was having problems getting it to run because the carburetor was running to lean and would only run with the choke just about all the way on. He had the carburetor rebuilt and the other day I installed it and when I finally got it to run it still runs lean and I also have to have the choke just about all the way on in order for it to run. I am looking for solutions or ideas as I'm lost as to what do next. I thought maybe the carburetor was still the problem but the techs say there maybe other problems. It does have a fuel pump but don't want to just start replacing parts. Any ideas and thoughts would be greatly appreciated.

Bob M · Nov 7, 2016

Does it have a Marvel-Schebler USX aluminum carburetor, or other??

kub6040 · Nov 7, 2016

Check for manifold leaks.

Vern A · Nov 7, 2016

No manifold leaks

Vern A · Nov 7, 2016

Yes it does. A USX 32-1

Steve@Advance · Nov 7, 2016

I believe the intake and exhaust manifold bolt together for heat transfer. Any possibility of an internal leak, exhaust getting into the intake?

Other areas of the carb to look at: Restricted main jet/wrong jet. Venturi choke missing, wrong size, upside down. Venturi tube missing, broken.

Have you checked the fuel pressure and volume? Some carbs have a screen in the fuel fitting, be sure it is clean.

Bruce from Can. · Nov 8, 2016

I no nothing of this particular tractor ,but for any gas tractor showing these kind of symptoms , I would eliminate any possibility of a fuel supply problem first . Any time someone says "I have to have the choke out to make it run right " is the first clue .

Mike M · Nov 8, 2016

Doesn't it have a load mixture adjustment needle ? You should be able to back the screw out more to over fuel it.

Vern A · Nov 8, 2016

How would you be able to tell if there is a leak between the intake and exhaust. Is there a test to find out if it is leaking internally. I have been looking to find how much pressure the fuel pump should put out and I am also going to check and make sure all fuel lines are not obstructed

Bob M · Nov 8, 2016

The USX is not one of M-S best carburetors. They are intolerant of even trace amounts of dirt/gum and are fussy to keep in adjustment.

Assuming no manifold leaks, etc. a freshly rebuilt USX running lean means the rebuild was not properly done. It's got either a plugged orifice or the float level is set low. A thorough cleaning and rebuild by a competent rebuilder should clear up the chronic lean condition.

Vern A · Nov 9, 2016

Thank you I will try that next. When I talked to the tech from yesterday tractor, he said they are rebuilt by professionals and there is nothing wrong with the carb. How does a person know if they put the right kit in for a USX 32. I guess when a person sends it in for a rebuild I should not have to tear it apart and check everything out.

J. Schwiebert · Nov 10, 2016

Have you checked fuel pump output? Pump pressure is low a couple of pounds will be good. Do you have a vacuum gauge? If so have you checked the vacuum? What happens when you open the throttle quickly? Send me an e-mail and include your phone number and we can discuss it in more details. J.

Vern A · Nov 10, 2016

Will do. I am putting a new fuel pump on it on Saturday cause the old one has a slow leak so I'm going to start there and make sure all the the fuel line connections are tight and free from any blockage. Will keep in touch. Thanks

Lean carb on 1800 Oliver

Vern A

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Bob M

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