LA 110 Lawn tractor - trying to tune up

[jeremytl]

Hey folks,
I have the JD LA110 lawn mower. Its a 2007 model, has served me wonderfully over the years. I give it a tune up every spring, which is what I did this evening. But lately it has been running rough and my regular tune up isn't fixing it. My regular tune up is oil change, clean or new plug, lube all points with grease gun and change air filter. The only way I can really explain how it runs rough would be to crank it up this evening and take a short video and post it to youtube, then I can post the link here. I just wanted to double check if that would be okay to do so before I broke any rules.

 

[RG1]

You should also change the fuel filter, especially with all the ethanol and other additives that get put in fuel these days. You may have picked up some water somewhere. If your fuel sat for very long in it, there's a good chance your carb is gummed up a bit inside. Try either Star-Tron or Sea Foam in your fuel. Both work very well at cleaning sludged/gummed up carbs, and Star-Tron will help if there's a little water in the fuel. If they don't work, you may have to take the carb off and take it apart and clean it with Gumout or some type of spray carb cleaner.

 

[jeremytl]

thats good stuff, RG1, thanks.
Here is the video I promised, I had a chance to pull it out of the shed today:

https://www.youtube.com/watch?v=Vzouy449nww

 

[RG1]

You've got dirt (small though it may be) in the high speed circuit of the carb.


Take it off and apart, and spray everything you can get at with a good carb cleaner. be careful putting the float bowl back on so you don't roll or wrinkle the gasket. Try to remove any of the jets you can get out so you can spray their seats and orifices. just pay attention too how you remove what from where. it isn't that hard to do.

 

[jeremytl]

I'd be grateful for any advice on how to do this or if there is a how-to guide online, this is a little above and beyond my mechanical experience.
Many thanks!

 

[RG1]

If you aren't sure you can do it, or lack the experience, you'd probably better off letting your dealer do it for you.

You can look at the carb here at JD parts, and also see and order either the complete repair kit or a partial repair kit-

John Deere - Parts Catalog

 

[jeremytl]

I found this on google, is this a legit try??

Find the John Deere mower's carburetor on the middle of the engine's right side. It is comprised of a distinctive black bowl with a small needle valve on its bottom. Adjust this valve all the way to the right, then turn it back to the left once. This needle valve is an air adjustment valve for the John Deere mower that controls the intake of air into the carburetor. An incorrect air intake will cause the carburetor to sputter.

Run the John Deere mower's engine and check for sputtering and other loud noises. Turn the needle valve to the left and right and try different tightness configurations on the valve in order to fix the carburetor and end the John Deere mower's sputtering.

Alter the carburetor's air intake further by checking the gas tanks's fuel cap. Unscrew the fuel cap and find its vent hole. This controls the flow of air into the gas tank and in turn affects the flow of air passed from the tank to the carburetor. This vent hole should not be filled up and blocked with debris or buildup.

Slide a small pipe cleaner into the John Deere's fuel cap vent hole and push out any buildup. Wipe off the cap with a cloth and screw it back onto the tank.

Place a pan under the bottom of the John Deere mower's carburetor if the engine is still running roughly. Loosen the nut on the underside of the carburetor's bowl with a socket wrench. Some gas will drain out. Your pan will catch it.

Remove the John Deere's carburetor nut after the gas has drained, then slide off the carburetor bowl. Place the nut in a carburetor cleaning solution and scrub it with a wire brush.

Clean the carburetor bowl by wiping it with a cloth.

Set the carburetor back into place on the John Deere mower's engine and fasten it into place by inserting its nut with the socket wrench.

 

[RG1]

Some of that may work for you. I didn't post it all because you said it was over your head. The last part of that is the only thing I'd really look at. Water and/or dirt will collect in the float bowl that it describes taking off. Just getting the water and/or dirt cleaned out can sometimes fix your issue, but I have had to re-build enough of them now to know the sound that yours is making in the video is a plugged up high speed circuit jet.
The fact that it idles, but then starts the missing as you throttle up is the give away to that.

If you go to my link, then look at the carb diagram at the right by mousing around over it, you can see all the parts and what jet is the high speed circuit. Then you can go too the column to the left and click on the repair kit links just below the carb link and see what they show will be in each one.

 

[jeremytl]

I found where you are talking about but the red box around part 25, there isn't an arrow pointing to where in the carb this jet is. Also, when they say high altitude, is that where you are referring to the high speed jet? I don't see high speed jet listed in the parts. Just trying to make sense of the diagram.

 

[RG1]

The main jet (#25) is the high speed circuit- the jet that regulates the amount of fuel at higher speeds once you get up off idle. The high altitude jet is what you would need to correct the air fuel mixture in higher altitudes such as the rocky mountains etc.

There are several things to be careful about when removing the carb. Don't force or tear any of the gaskets between the carb and airbox or the carb and the side of the engine block.

Start by draing the fuel bowl as stated in your post, then removing the air box and the fuel line and linkage from the carb, then loosen and remove the carb from the block (usually two long screws or bolts hold it on that pass through the carb body). Place it on your bench and remove the fuel bowl completely by removing the two bolts (14). The float is hung from a hinge pin (11). Remove the pin and then drop the valve (9) out of the bottom of the carb. pay close attention to what came from where and in what order. Spray carb cleaner up inside the valve recess. (wear eye protection when using carb cleaner spray)

Spray the inside of the bowl well and drain out. Spray into the throat of the carb where gasket #8 fits, and through the opposite end as well. spray every little nook and cranny you can from either end. I'm very hesitant to tell you to take anything else out, off, or apart since this is new to you.

Make sure when putting things back they go back in in correct order and position. make sure to put the float bowl gasket (13,17) back exactly as it/they came out. make sure to tighten the bolts that hold the bowl to the carb body up snuggly, but do not overdo it. Same for the bolts that hold the carb body to the block.


If this seems like more than you are comfortable with, then you're are a lot better off having a small engine repair shop or your dealer do the carb cleaning for you. If you screw things up, you can end up costing yourself a lot more money than just the carb cleaning cost will be.