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Back Story. Rider ran great last fall but I had to jump start it every time I needed to use it. So this spring I figured I will solve the problem and install a bran new battery. I did however the tractor started right up and then stalled. I could not get it to run unless I poured a little gas down the carb and then it would start and die again. I pulled gas line off carb and had fuel flow when turning the engine over. So I pulled the carburator to clean it. Put it back on and same problem. Not sure why a complete disassembly and clean did not fix it. I am thinking maybe float was not opening and could pin hole in it.

For $20 I ordered a new carb on Amazon. Put it on and it fired up right away. Now It is surging and you can see the throttle rod that comes from governor moving when this happens. If I hold the rod in my hand it will run smoothly. Now what do I do and why a new carb would cause this?

I have more information now. I siphoned all the gas out of the tank. I replaced with brand new ethanol free gas. I installed a brand new fuel filter and A new spark plug. Still not running great. So I looked at my carburator again thinking I might not have installed the choke mechanism correctly. This is where I noticed the spring on choke what not connected correctly. I also noticed the plastic piece on the new carb was different than the one I replaced so I took the plastic piece where the choke arm connects off of the old carb and replaced it onto the new carb and made sure the spring was correct so it would retun the choke back to open after the choke was engaged. Seems to run better however now I have a different problem. I still get some surging at mid to high speed unless I move the throttle forward so the choke is about 1/2 way on. It runs great with the throttle pulled down to low speed. What could be causing this?

Surging on a governed engine is always a lack of fuel.
Two ways this happens
1) not enough fuel being delivered to the main jet in the carb
or
2) air getting in after the fuel was added.
Check for the latter by saturating the area between the carb & the engine with WD40 FROM A TRIGGER PACK NOT A SPRAY CAN>
If you get white smoke or the engine changes speed then you have an air leak.

If not then you still have a fuel blockage.
And double ditto about getting defective parts off Amazon / Ebay .
OEM means it came from the same factory.
It does not meant the product actually works.

https://www.greenpartstore.com/John-Deere-Model-LA115-Lawn-Tractor-Parts.html

https://www.greenpartstore.com/John-Deere-Carburetor-Repair-Kit-MIA11477.html

https://www.green-parts-direct.com/...d-31p6770239b1-fuel-air/AD-4275-177868-155169

scroll down page for your carburetor, JD OEM carburetor $125.57

bertsmobile1 said:

Surging on a governed engine is always a lack of fuel.
Two ways this happens
1) not enough fuel being delivered to the main jet in the carb
or
2) air getting in after the fuel was added.
Check for the latter by saturating the area between the carb & the engine with WD40 FROM A TRIGGER PACK NOT A SPRAY CAN>
If you get white smoke or the engine changes speed then you have an air leak.

If not then you still have a fuel blockage.
And double ditto about getting defective parts off Amazon / Ebay .
OEM means it came from the same factory.
It does not meant the product actually works.

Click to expand...

Getting ready for a graduation open house so have not had time to dive in again. For now I run with choke partially on. I have 2 thoughts in mind. Take new and old carburator apart. Put the original main jet into the new carb. Or B take float and needle out of new carb and stick in old carb and see if it runs.

Paul_Aris said:

Getting ready for a graduation open house so have not had time to dive in again. For now I run with choke partially on. I have 2 thoughts in mind. Take new and old carburator apart. Put the original main jet into the new carb. Or B take float and needle out of new carb and stick in old carb and see if it runs.

Click to expand...

Well that seemed to work. Took the new carb off and put the main jet in from the Old carb that looked like it has a bigger orfice. Had to take a part and reassenble a couple of times before I got it right. Is it me or is it hard to get the plastic piece lined back up with carbs and one big o ring and bowl? First time would not run with out choke. Second time leaked fuel like crazy from float bowl. 3rd time must have got everything right because it runs like new now.

If you have the Nikki carb with the white plastic dodad between the float bowl & carb body, then the trick is to fit the rubber seal, fit the plastic bit into the body then put the bowl on.
And yes they are fiddley
There is also 2 different rubber seals.

bertsmobile1 said:

If you have the Nikki carb with the white plastic dodad between the float bowl & carb body, then the trick is to fit the rubber seal, fit the plastic bit into the body then put the bowl on.
And yes they are fiddley
There is also 2 different rubber seals.

Click to expand...

Yes, not sure what brand they call the carb but sounds about right. It was hard to tell at first if the O-ring is supposed to fit under the plastic or just around the outside but inside the float bowl which is the way I think is correct. You also have to make sure the entire center section of the o-ring is lined up right. Then there is that main jet that just sits on top of the stem pick up and fits inside the plastic. I am used to Mikuni's or Kehnins like on snowmobile, bike and quads, Much more robust design.