Car enthusiasts and mechanics aren’t the only ones to clean their carburetors. It’s actually something that many lawn mower owners do on a regular basis. Now, if it’s not something you have done before, then you’re probably a bit worried that you might do more harm than good. But if you take your time and follow my guide, you’ll be able to add small engine mechanic to your list of skills. The best part is that your lawn mower will run better than ever. So, let’s dive in and go over how to clean your lawn mower’s carburetor.
Cleaning a Lawn Mower Carburetor (The Short Explanation)
There are a few necessary steps to clean a lawn mower carburetor thoroughly. This includes removing, dismantling, cleaning, replacing damaged parts, then rebuilding the carburetor. Here are the steps you’ll need to follow if you want to carry out a comprehensive carburetor cleaning.
- Externally Clean the Carburetor
- Remove the Carburetor
- Partially Dismantle the Carburetor
- Internally Clean the Carburetor
- Replace Any Damaged Parts
- Reassemble the Carburetor
- Install the Carburetor
Why You Might Need to Clean Your Mower’s Carb
The signs of a bad carburetor are pretty easy to spot once you know what to look out for. If you’re having some trouble with your lawn mower, then you’re probably familiar with some of the symptoms already. If you’re not too sure what the signs are, here’s a list of what I believe are the most common issues.
- The Engine Won’t start
- The Engine Won’t Idle
- Jerky Engine & Backfiring
- Surging & Sputtering Engine
- The Engine Doesn’t Accelerate (Lawn Mower is Running Slow)
- Carburetor Keeps Flooding
- Black Smoke from the Exhaust
- Gas Leaking from the Carburetor
- Mower Only Runs with the Choke On
What You’ll Need On Hand to Clean Your Mower’s Carburetor
Before you head out to your lawn mower, you need to gather some tools and a few bits and pieces. Here’s a list of all the materials you’ll need.
- Socket Wrench Set
- Screw Driver Set
- Pliers
- Needle Pliers
- Hose Pinch Off Pliers
- Nylon Brush
- Thin Wire
- Carburetor Spray Cleaner
- WD-40 Spray
- Cleaning Cloths
- Air Compressor (Optional)
- Carburetor Repair Parts Kit (Engine Specific & Optional)
How to Clean a Lawn Mower Carburetor (A Simple Guide)
There are a whole bunch of carburetors available for lawn mowers and each requires a slightly different method of cleaning. But generally, the steps stay the same. So, let’s have a look at what you’ll need to do.
Lawn Mower Cleaning
The first step is to clean off the outside of the carburetor. I find that WD-40 and a small nylon brush, like a toothbrush, work best. Anything more aggressive than nylon could damage the soft alloy metal of the carburetor.
You want to make sure to get all the clippings and dirt off the outside of the carb so that nothing falls into the engine when you remove the carburetor.
Removing the Carburetor
Start by removing the cover of the air cleaner and pulling out the air filter. You might need to use a screwdriver to remove the cover. Once you get both items removed, set them aside for later.
The next step is to remove the air cleaner base. This is the back of the air cleaner that the filter sits inside. So take your socket wrench and remove the bolts that hold the base to the carburetor. Again, set these parts to one side for later.
Now, it’s time for the fuel line. If your lawn mower has a cut-off valve, then switch it off. This will stop fuel from leaking from the fuel tank. If your lawn mower doesn’t have a valve, then a pair of fuel line pinch-off pliers will work fine.
Next, take a pair of pliers and remove the fuel line clamp. You’ll just need to move the clamp an inch or two down the fuel line. Once you have the clamp moved, slide off the fuel line. I find that giving it a twist at the same time as pulling helps to get the line off.
Now it’s time to disconnect the carburetor from the engine. So, take your socket wrench and remove the bolts holding the carburetor to the engine. Once you remove these bolts, the carburetor should come free of the engine, so be careful it doesn’t fall.
The throttle link cable is the final thing holding the carb to the mower. You can easily remove this link by using your pliers. Once you get the link off, you should be able to pull the carb completely away from the mower.
Dismantling the Carburetor
Now that you have the carburetor free, I suggest moving to a workbench or table with some good lighting and a bit of ventilation.
So, tip the carburetor upside down and locate the fuel cup’s center bolt. Use your socket wrench to remove the bolt, then remove the fuel cup from the carburetor.
Then take your needle nose pliers and remove the pin holding the float in place. Once the pin is removed, the float should come away from the carburetor.
Now it’s time for the jet. If you look where the cup bolt screws into the carburetor, you’ll find a screw. Use one of your screwdrivers and remove the bolt, being careful that the jet doesn’t fall out as this screw is holding it in place. Next, tip the carb into your hand so that you can catch the jet. It should fall out, but it might need a bit of help.
Cleaning the Carburetor
Now that you have the carburetor stripped down, it’s time to run through how to clean a lawn mower carburetor. So, grab your carburetor spray cleaner and give the whole carb a good spray. Allow the spray to soak into all the dirt and grime. Carb cleaners also act as a degreaser, so they will take care of the grease and oils on the outside.
Next, use your brush and cleaning cloth to remove all the dirt from the carburetor. Once this is done, you can take a look at the carburetor ports. These are the internal holes/passages within the carburetor. The ports are usually about the same size as the straw attachment of the cleaner. So, place the carb cleaner into the ports and give them a quick spray. The force of the spray normally shoots out any dirt.
The next step is to clean all the small parts you removed from the carburetor. Again, give them a good clean with the brush and the carburetor cleaner. Then, use your small wire and clear out any blockage in the jet. This is the main area that causes problems with the carburetor, so be sure to get the jet completely clear.
Optional Stage – I mentioned a carburetor repair parts kit in the list above. This kit you can get for your carburetor includes items like washers, o-rings, and gaskets. With this kit, you can replace all the perishable parts of the carburetor and thoroughly clean your carb. So if you decide to use a repair kit, be sure to remove the old parts from the carburetor.
Rebuilding the Carburetor
Now that you have the carburetor all cleaned up, it’s time to put it back together. As long as you install all of the parts you removed. So, to rebuild the carburetor, follow the list below in order.
- Install the Jet
- Install the Jet Retaining Screw
- Attach the Float
- Insert the Float Pin
- Attach the Fuel Cup
- Install the Fuel Cup Bolt
Reattaching the Carburetor
You’ve almost finished learning how to clean a lawn mower carburetor. The final step is to reattach the carburetor to the mower. So, if you follow the steps below, you’ll have your mower up and running in no time. All you’re doing is reversing the process you used to remove the carburetor.
- Connect the Throttle Linkage
- Position the Carburetor on the Lawn Mower
- Install the Carburetor Mounting Bolts
- Connect the Fuel Line & Clip
- Attach the Air Cleaner Base
- Install the Air Filter
- Install the Air Cleaner Cover
- Release the Fuel Line Clamp
Riding Lawn Mower Carburetor Cleaning vs Push Mower: Is There a Difference?
The method of cleaning a carburetor doesn’t really change between a walk-behind lawn mower to a riding mowing. If anything, I’ve found cleaning a riding lawn mower’s carburetor a bit easier because they tend to have better access to it. I don’t have to kneel on the floor like I do when working on a walk behind because it is so low to the ground. Once I finish my homemade mower table, this won’t be a problem anymore. So, if you’re able to elevate your push mower, then I would say cleaning the carburetor on a riding lawn mower is the same as cleaning a push mower’s carburetor.
Is There a Simpler Way to Clean a Lawn Mower Carburetor?
I’ll be the first to put my hand up for a simpler way to clean a carb, but not if it’s less effective. Cleaning a lawn mower carburetor without removing it is an option you can use to clean out any fuel gum residue from bad fuel.
You’ll find that this method solves a lot of the problems associated with a bad carb, like getting rid of a sticking float or a restricted jet. But if you struggle with access to the carburetor or blocked carb ports, I’d recommend removing the carburetor completely. Products like carburetor spray cleaners do a good job, but not when it comes to a chunk of grass in the jet. If you try the spray cleaner, but it doesn’t fully solve the issue, you will probably get better results by removing the carburetor and cleaning it thoroughly.
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