Mountfield mower carburetor cleaning. How to Repair Small Engines: Cleaning…
Mountfield mower carburetor cleaning
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Mountfield Lawnmower Problems and Solutions
Despite a few common problems that your lawnmower may have, Mountfield lawnmowers are trusted because they are compact, lightweight, and easy to handle.
These ride-on lawn mowers are equipped with ample power from the Stiga engine, and the raised seating offers superior sitting visibility — which is suited for mowing for longer hours.
As a Mountfield lawnmower, there are a few common problems that you should be aware of.
These include the blade bosses shearing off, broken shear key, and gas tank or gas line blockage.
Read on to learn how to troubleshoot these common problems and find the solution to your problem.
Ailelan Lawn Mower Seat Cover
- Multiple s for gloves, rags, pruners, tools, etc.
- Easy to install
- Suitable for most mowers
Here are some of the most common Mountfield mower problems:
Blade bosses sheared off
If your Mountfield lawn mower blade bosses sheared off, you are not alone.
This common problem affects many mowers and can be very costly. However, there is a solution for this problem that is very affordable and easy to install.
A new blade boss is an inexpensive and simple solution to this problem. You can purchase them from most dealers online.
The installation process is simple and involves tightening the blade bolt to the correct torque setting.
Alternatively, your local dealer should be able to help you install a new boss.
If you are unable to remove the old blade bosses yourself, you can purchase a push mower blade replacement kit. These kits are cheap and easy to use, and they include replacement nuts and blades.
They can be found at home improvement stores for a few dollars. If your blades have already been damaged, you may have to replace them all.
A new set of blades will usually cost just a few dollars, and you can reinstall them in less than ten minutes.
Gas tank or gas line blockage
If you’re experiencing problems starting or running your mountfield mower, it’s time to diagnose the problem.
There could be several reasons for this problem, including a dirty gas tank or blockage. A fuel filter may be clogged or the fuel line itself is obstructed.
While the task may not be huge, it’s important to follow safety precautions when working with your lawn mower.
A damaged carburetor can also cause the engine to hydro-lock. Hydro-locking occurs when gas in the cylinder prevents movement. This can cause a no-start condition, so make sure to use a fuel stabilizer when transporting your mower by trailer.
The fuel stabilizer will prevent this problem while winterizing your Mountfield mower and recommissioning it in the spring.
If the fuel tank is cracked, it’s most likely the result of a malfunction. A low-hanging shrub branch or other object may have fallen on the lawnmower and damaged the tank. In the worst case scenario, the fuel line could snag on a shrub and break off.
Luckily, replacement of a fuel tank can be a simple process. The fuel line on your mower is typically held in place by spring clamps.
A clogged carburetor
To start troubleshooting a clogged carburetor on a mountfield mower, you must make sure that you have a good understanding of how to inspect a carburator. First, make sure that you check the level of oil.
You should do this every time you mow, or at least once a month, depending on the frequency of use.
Check the oil level regularly as well, since oil consumption can be much higher on sloped ground or if the oil blows through the crankcase breather. If you’re having trouble starting your Mountfield mower, it’s likely the carburetor is clogged.
Another problem that could be causing a clogged carburetor on a Mountfield mower is the choke.
This is a part of the lawnmower that mixes air and fuel for combustion before entering the engine. The carburetor has several passages, depending on the throttle position.
The idle circuit is the passage that allows fuel to enter the air stream while the mower is in idle mode.
When you are running on full throttle, fuel enters the main jet. The choke helps to provide extra fuel during start-up and during cold conditions.
If you can’t find the problem, you may need to replace the entire unit. The float and the bowl are both located underneath the carburetor.
When you apply a voltage to the coil, the solenoid will open the valve and allow fuel to enter. But be careful, because they can get stuck and clogged.
Regardless of the method used, it is essential that you check your carburetor before starting your mower.
Broken shear key
If you notice that your shear key is not releasing the blade, you might have broken the shear key on your mountfield mower.
This can happen for several reasons. Sometimes it happens because the mower has been in storage for some time.
Occasionally, this may be the case and you need to take it to your local dealer to repair it. Broken shear keys on Mountfield mowers are quite common, but it’s still important to know how to fix them in case you break them.
A broken flywheel key is one of the most common causes of poor running or no-start problems in lawn mowers. A faulty flywheel key is caused by a mower striking a non-mowable object.
The crankshaft is solidly connected to the cutting blade, but if the mower hits an obstacle, the crankshaft could become broken.
A faulty ignition module or a malfunctioning safety interlock system can also result in a broken flywheel key.
Oil level
If you notice that the mower doesn’t start or runs at all, the first thing to check is the oil level. Check the dipstick, which is usually attached to a small screw cap that is similar to the gas tank cap.
Then, clean the dipstick by wiping it with a cloth. Look for high and low marks. The oil level should be in between those marks. If you notice that the oil level is too low, the next step is to check the fuel level.
Checking the oil level is an easy and quick task. It’s easy to do while the engine is turned off and the mower is parked on a level surface. Locate the dipstick, which is usually labeled “oil” or “oil can” with a contrasting color.
The cap also acts as the oil filler. Check the oil level with the dipstick.
The upper mark indicates that the level of the oil is full, and the lower mark shows that the oil is low. There may also be a hatched mark on the dipstick to indicate that it’s acceptable to do so.
If you see the mark on the dipstick that says “additional oil is needed”, make sure that the level is higher than that.
You may notice the exhaust valve spitting out gas continuously. This is a result of the exhaust valve being stuck open. If the exhaust valve is stuck open, apply WD40 to loosen the stem. If you feel pressure, the intake valve is partially open or closed.
When the intake valve is closed, the mixture is pushed out of the chamber during the compression stroke. The carburetor should be cleaned and the engine rebuilt if the mixture is too high.
No spark
If your mountfield mower does not produce a spark, there are a few different things you can do. To start the mower, you will need to make sure that the control wire is connected correctly to the flywheel brake assembly and the engine coil.
When this is not done, the engine will not produce a spark, and this is a common cause of no-spark problems.
To test if the control wire is loose, you will need to remove the cowl on top of the engine and remove the flywheel if necessary.
If the problem is fuel-related, try cleaning the carburetor. If there is water or dirt in the float bowl, it can block the spark.
Another cause of a no-spark condition is the ignition coil failing. If the ignition coil is failing, you will need to replace it.
Once you’ve removed the spark plug, you can replace it. But you may not have noticed any improvements in performance.
To check the ignition coil, you will need an in-line spark tester. Insert this tester into the spark plug boot and test for spark. If the tester shows no spark, then the ignition coil is likely to be the problem.
If this does not work, then you should consider another possible cause. If the ignition coil is faulty, the mower will be difficult to start.
A good place to start your mower is the garage. Alternatively, you can try a portable spark tester.
Clogged needle valve
If you’ve noticed a slow idle on your Mountfield mower, it may be the needle valve. The needle is located near the carburetor.
Remove the carburetor bowl and check the needle. It should be free of debris. If it’s not, it’s probably clogged. Look underneath the carburetor for a spring that holds the needle valve to the float hinge.
If it’s loose, turn the jet clockwise a quarter turn. Be careful not to over tighten the jet; it could damage the soft tip. The opposite is also true.
First, check the float. On some engines, the float may be clogged, allowing fuel to trickle out.
Another possibility is that the engine is upside-down, causing the fuel to leak out. If this happens, the float may no longer operate properly and a fire could break out.
The problem may also be a broken cable between the float and the engine. Once you find the problem, repair it as soon as possible.
Mountfield Lawn mower Problems: Conclusion
If the needle is sticking or sluggish, try to disengage the linkage between the throttle body and air injector.
If you can, increase the idle speed slowly. After that, spray a solution of lubricant on the needle valve.
Once the valve is clean, restart the mower a few times. If the problem persists, visit a store to have the issue fixed.
You can also contact a manufacturer of Mountfield mowers to ask them for help.
Don’t Google small engine repair near me the next time your lawnmower sputters. Learn how to do it yourself. Small engine repair is all about a clean carburetor.
Family Handyman
Introduction
Solve most lawnmower or other small engine starting problems with a simple diagnosis and a carburetor cleaning or rebuilding. It will only take a few hours, and you’ll avoid the minimum 80-plus-parts repair bill.
Materials Required
If you can’t get a small engine started, it takes too many pulls to get it going, or it runs poorly, ask yourself this: Did it sit for a long time with gas in it? Like over the winter? If so, your problem is most likely a corroded or gummed-up carburetor. Small engine repair shops earn about 50 percent of their revenue by cleaning or replacing carburetors sidelined by old gas. Look at your lawnmower carburetor next time you sharpen the blades or complete a lawn mower tune-up.
Before you start taking things apart, take a minute to confirm the carburetor is the problem. We’ll show you how to do that, as well as how to clean, rebuild or replace a lawnmower carburetor. Either way, you’ll save about an hour of shop labor (about 80). You can complete the carburetor rebuild project in a single morning, including the time scouting for parts.
How to Find Lawn Mower Carburetor Parts and Prices
Whether you buy parts from a local small engine repair shop or online, you may need all this information:
- Machine brand (Toro, Snapper, Honda, etc.), model and serial number.
- Engine brand and serial number (Tecumseh, Briggs Stratton, Honda, etc.). The engine model and serial number are usually located on a plate above the spark plug.
- You may also need numbers from the old carburetor itself, usually stamped onto the carb body or its mounting flange.
- You can buy locally, or try smallenginepartswarehouse.com or psep.biz.
Where is the Carburetor on a Lawn Mower?
The carburetor is usually located towards the top of the engine, and is connected to the gas tank.
Lawn Mower Sputtering? Here’s How to Fix It
Lawnmower maintenance is a crucial part of keeping your mower running properly. Regular maintenance promotes the overall health of your lawnmower and its ability to properly operate. But even with regular maintenance, there may be times when you experience issues with your mower. One common problem among lawnmowers is sputtering. Lawn mower sputtering is generally an inexpensive and easy fix that can be done on your own as part of your regular maintenance.
In this article I’ll share what causes a sputtering lawn mower, and what you can do to fix this common problem.
About Lawn Mower Engines
The engine of your mower relies on the right combination of fuel, air, and a spark (for combustion). Your mower needs each of these to prevent the mower from sputtering and eventually dying.
For the most part, many of the issues that cause a sputtering mower can be fixed by the weekend warrior.
However, there are times when it is best to use a professional for the job.
You’ll want to check a few items to determine what’s causing your mower to sputter, and that will determine if it’s a DIY fix, or you need to call in a professional.
Let’s look at some reasons why your lawnmower may be sputtering and how you should address each of these issues.
Identifying the Cause of a Sputtering Lawn Mower
Below are some of the more common reasons for sputtering lawnmowers and how they can be resolved.
Old Fuel or the Wrong Fuel
The gas you get at the local gas station will generally contain about 10% ethanol. It’s cheaper than pure gasoline, and works fine for cars, but I don’t use it in my mower because it’s low quality.
Ethanol burns quickly and can potentially melt plastic parts, leading to sputtering in your mower. And if you use ethanol blended gas, only buy a little at a time.
If it sits in your garage for more than a couple of months it will go bad and can lead to a sputtering mower.
You can use a fuel stabilizer to extend the life of the gasoline, but I recommend using an ethanol-free gas. It’ll burn cleaner and help your mower to start on the first pull and roar like a tiger.
I use 4-cycle Tru-Fuel in my Honda mower, and love it. It’s pricey, but I highly recommend you try it. You can buy it locally at most box stores, or you can order it online (Amazon link).
Clogged or Dirty Air Filters
Dirty air filters are one of the most common reasons lawn mowers sputter.
Dirt can be present in the apertures that lead from the carburetor and the fuel filter and interrupt the flow of fuel supply to the combustion chamber.
You want to be sure to clean or replace dirty air filters.
Paper air filters will need to be replaced. But you can generally clean foam air filters with a drop of liquid dish soap and warm water.
After cleaning the air filter, squeeze dry and air dry.
My Honda mower uses a paper air filter which I replace every year as part of my spring mower tune-up.
During the summer, I remove it and blow the dust and debris off before each mow.
Dirty Fuel Filters
Any filter will get dirty with time, and just like the air filters, fuel filters in a lawn mower need to be clean.
Replace yours if they’re dirty.
Clogged fuel filters prevent the flow of gasoline to the engine which can lead to a lack of fuel needed for proper functioning.
This imbalance of air and fuel in your engine can cause your mower to sputter and run rough.
A Bad Gas Cap
Misfires can occur with an improperly vented gas cap on your mower.
If your gas cap has improper venting, too much air can be allowed to enter the gas tank (or too little). This can cause a vapor lock.
It’s an easy fix – just replace the cap if it is damaged or bent or if you see that the vent hole is restricted.
That Carburetor is FILTHY
Gunky deposits can occur in the apertures and carburetor.
This buildup is from the sticky by-products of hydrocarbon and combustion.
Using a carburetor cleaner spray (this one on Amazon is what I use and swear by) on a regular basis can loosen dirt deposits and keep your mower’s apertures and hoses clean.
I give my carb a shot every time I clean my air filter before I mow.
Water in the Fuel Tank or Fuel Line
Water prevents the mower cylinder from properly igniting. Remove the cap and check the gas tank for evidence of water (if you see the liquid separating or looking like two different colors).
If there is water in your tank, siphon or drain it, then add new gas.
After old gas in the line works its way through the mower’s engine it should stop sputtering and run like new again.
Check the Spark Plug
Worn or damaged spark plugs make the engine difficult to start. If the plug is damaged, worn, or deteriorating you should replace the plug.
If the tip is fouled or dirty, just clean it with a wire brush and reset to the mowers manufacture’s settings.
You can also look into purchasing another brand of spark plug to see if the mower runs better with a different brand. The plug that comes from the factory with some mowers doesn’t work great on some lawn mower brands.
The spark plug is generally not the first thing I’ll check for a sputtering mower. But a dirty or damaged plug can sometimes be the cause.
Your spark plug is an easy item to replace, and costs about 8 at your local hardware store.
I replace my plug every other year as part of my annual maintenance routine. If it has been more than two years since you’ve bought a new plug, I recommend replacing it as part of your tune-up to fix your sputtering lawn mower.
Your Carburetor Has Issues
Some carb cleaning spray will help if your carburetor is simply dirty, but sometimes there are other issues that can cause lawn mower sputtering.
The carburetor affects how well the mower runs. The wrong blend of air and fuel can cause the carburetor to run rough.
The carburetor must have the right amount of air and fuel to run correctly, and while the average weekend warrior can probably find and remove his mower’s carb, due to its complexity, the carburetor can be tricky to clean or repair.
If you’ve tried everything else on this list, it’s likely a carburetor issue and your mower may require professional service.
A professional can determine the repairs, cleaning, and replacements needed. They’ll then get the carburetor working properly.
First, check to see if your mower is covered by a warranty of any kind. If it’s not, find a local small engine repair guy (or gal), and have your mower serviced.
It’ll be cheaper than you expect.
A Dirty Mower Deck
Caked grass on the mowing deck can cause the mower to sputter.
If you have tall or wet grass you may have noticed that your mower started sputtering as you mowed your lawn.
Check the underside of the mower for excess grass caked on.
Use a wrench to remove the spark plug to prevent the mower from turning on while you work. Then scrape the excess grass using a scraping tool such as a paint scraper.
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by Sarah The Lawn Chick
Sarah’s blog, Lawn Chick, is read by over 2 million homeowners each year and she is regularly cited as an expert source of lawn care knowledge by major publications. Her goal is to meet you where you are, and help you achieve a yard you’ll be proud of. Ready to take the next step toward improving your lawn? Grab her free lawn care cheat-sheet: What to Do When. Take the Guesswork Out of Lawn Care, or upgrade your garage by browsing her favorite DIY lawn care products.
thoughts on “ Lawn Mower Sputtering? Here’s How to Fix It ”
I am a 62 year old female just having to learn how to care for my own mowers, riding push. Your article was more informative than the many others I’ve read! Thought it was sputtering due to the spark plug but now I’m sure it’s the carburator. FYI, when my husband was the main mower man both mowers spent more time in the shop than on the lawn and the cost of repairs would have bought me a brand new one. If it didn’t start immediately off it went to the shop. It never cost less than 100, usually more plus 60 for a 1 mile pick up. I really think the repair man had my husband pegged for a sucker and that may be accurate. That’s the main reason I decided to care for them myself. Since I became the main mower lady and actually read articles like yours it’s smooth riding! Lol Thank you so much for your help.
Thanks, Teresa! Your article made my day – I’m so glad you found this helpful and are tackling these projects yourself!
My Lawn tractor Craftsman R1500 30″ deck, Mod.#247.29900 by MTD, sputters (like running out off gas) after 20-25 minutes of operation and eventually dying. After cooling off for 30 minutes or so, it starts and run again. It is frustrating! Can you please help my with my problem? I installed new fuel filter, put new gas. (I run out gas as season changes). What else can I check to make it work? Thank you in advance Mick T.
Hey, Mick – It sounds like you may have a clogged gas cap vent. The gas cap on most lawn tractors has a small hole in it which allows air to get into the tank. This is important because as your mower burns fuel, that empty space in the tank needs to be replaced with air for the correct mixture of fuel in the engine. If air can’t enter the tank as your mower burns the fuel backward pressure is created and your engine will struggle to get enough gas, which is why you may hear your engine surging or sputtering the same way it would if it was running out of fuel. Typically when I hear that the mower works well at first, then this issue happens after 20 minutes or so, this is the culprit, because that’s when you’ve used enough of the fuel for the pressure imbalance to become an issue. A good way to trouble-shoot and determine if this is definitely the issue is to run the mower, and when this happens and your mower won’t start, open up the gas cap and then put it back on. This will relieve the pressure, allow air in the tank, and get things back in balance. If the mower starts up right afterward and runs fine, you’ve identified the problem. Clearing the vent is easy – just find something small enough to slide through the vent hole and clear out any dirt or debris that’s in there, and you’re good to go. If it’s cold where you are, you may need to bring the cap inside to warm it up first as the solids in there may be frozen, making them tougher to remove. Hope this solves your problem!
Great help. My lawnmower was starting and sputtering and dying in a couple of seconds. Tried NEW GAS (the one in the tank was a year or more old) and it WORKED.
Mountfield Ride-On Mower
Joined 19 Apr 2021 Messages 6 Reaction score 1 Country
Hello. hopefully someone can help. we have a Mountfield ride-on mower (about 2 years old) which keeps cutting out at high revs. Ticks over fine on low revs, but stick it into high revs, it runs for a little while (30 secs to a minute) and then just cuts out. My partner has cleaned the carb, taken out the air filter, but it still does it. Could it be the dodgy battery or plugs? Any help gratefully received because I did my daily number of steps yesterday with the push mower!! Thanks in advance
Burnerman
Joined 7 Feb 2008 Messages 24,450 Reaction score 5,025 Location Northumberland Country
By all means try a new spark plug but the chances are its fuel starvation. can you tell us which machine it is? When it tries to pack in, give the engine some choke, if possible, and see if it picks up again. John
Treeze
Joined 19 Apr 2021 Messages 6 Reaction score 1 Country
Thanks. I’m pretty sure it’s a 1530H, but I’ll confirm for sure later. It doesn’t give you much chance to give it some choke, it just stops. It doesn’t sputter first, it just dies.
Burnerman
Joined 7 Feb 2008 Messages 24,450 Reaction score 5,025 Location Northumberland Country
That machine is likely to have Mountfields own engine, against the earlier Briggs and Stratton. No problem though, the carburettor will have to be removed for a clean, and an aerosol of carb cleaner is essential. Post a picture of the carb if you want to have a go! John
Treeze
Joined 19 Apr 2021 Messages 6 Reaction score 1 Country
OK, thanks. I’ll check the machine when I get home. Now I’ve started the thread, I’ll hand it over to my partner as he’s the technical one. He did clean the carb yesterday, but not sure if it was with carb cleaner or a quick rub on his shirt. Anyway, I’ll be back on here later with an update. Thanks again.
Treeze
Joined 19 Apr 2021 Messages 6 Reaction score 1 Country
It’s a 1538M. Fuel line was blown through, fuel filter was removed and replaced temporarily with a piece of pipe to eliminate a blocked filter, carb was removed and jets checked, float valve cleaned. I agree seems to be starvation but I can’t see how, all looks ok. I haven’t removed the plug yet. The battery is not good, was having to jump with leads to get started. Ticks over great, but bring up revs runs for short period then cuts out.
Burnerman
Joined 7 Feb 2008 Messages 24,450 Reaction score 5,025 Location Northumberland Country
Once the engine has started, the battery condition has nothing to do with your problem. Spark plugs failing under load and heat isn’t unknown so always best to fit a new one, just to rule it out. When you overhaul these carburettors it is essential to use a proper carb cleaner in aerosol, I have the luxury of a compressed air line too. Always look for rust deposits in the float chamber before you go any further. I’d take great care looking at the needle valve operated by the float, followed by the main jet and the emulsion tube directly above it but its only a cleaner plus compressed air that will really do. just blowing through jets with your breath isn’t enough. The fact that the engine runs for ever at slow speed but dies at high revs, where its using much more fuel has to indicate a fuel shortage at this time. John