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What Causes Lawn Mower To Surge? Read Here!

Written by Danica Rojero
Last Updated on April 12, 2022

Lawn mowers are powered by gas, electric or diesel engines. The gas engine is the most popular.

When you start a lawn mower, it must be properly primed or charged before it will run.

The primer pumps fuel into the engine and allows it to start. This can cause a surge if the lawn mower is not primed correctly.

Clogged Air Filter

Air filters are important parts of your mowers. They help the mower run properly by keeping the air clean and allowing the engine to burn fuel efficiently. You should always remove the spark plug wire before doing any repairs or cleaning. Doing so prevents injury.

A foam filter should be cleaned by using soap and warm water. An engine oil coating should be applied to it before it gets dirty. A paper filter should be replaced with a new one if it's too dirty for the user to see the light through it.

Wipe dirt out of the housing before you install the filter. Clean your air filter regularly. If the engine surge when you start it up, read on to learn how to fix this problem.

Dirty Carburetor

This is the most common cause of carburettor surges. Grime and dirt clog the internal parts of your faulty carburettor, making it unable to receive the proper amount of fuel. You need to remove the carburettor and clean it out with some carb cleaner to fix this problem. If you know how to do this, then follow these steps:

1) Remove the spark plug carburettor wire and disconnect the battery.

Disassemble the lawnmower carburettor. You must remove the air filter, fuel tanks, governor control link, and breather pipe to do this. Then clean the carburettor with an appropriate carburettor cleaner. Replace the carburettor if it's in bad shape or damaged.

Reassemble the mower parts by putting them back together in the correct order.

2) Reattach the battery and reconnect the spark plug wire. Start the engine and check whether the surge has stopped if it hasn't, repeat step 1.

3) Check the condition of the carburettor again. It may have been damaged during disassembly. In that case, replace it.

Fuel System Problems

Fuel tanks need to be cleaned regularly to avoid problems such as surging. Dirt or dust can block the holes in the tank cap. Rainwater can cause problems if it enters the tank.

Fuel lines should be cleaned regularly. You can clean them by using a fuel cleaner or draining the gas tank, and cleaning out the gas bowl.

Fuel levels must be kept low if you want to avoid engine damage. You should check the gas tank and gas filter regularly.

Vacuum Leaks

A loose carburettor unit will cause an engine to run poorly because it sucks in more air than needed. This causes the engine to be out of balance, causing poor performance.

Professionals should check Mowers before using them. Tighten bolts on the carburettor adjuster or air intakes. If this doesn't fix the problem, it could mean there are more serious issues with the mower.

Spark Plug Issue

Lawnmowers should rev up and down if spark plugs are damaged or have unbalanced adjustments. Check inside the spark plug if it has corrosion build-up issues.

Cleaning off the object's surface with a soft brush can remove rust. Adjustment is also important because you want to ensure the gap is correct. Changing the spark plug when it is damaged is necessary.

If you're unsure about changing a spark plug, consult a professional mechanic.

Incorrectly Adjusted Carburetor

If you fail to adjust the lawn mower carburettor correctly, lawnmower may rev up and down after a while. You can change the adjustment screw on most lawnmowers.

You should follow the instructions given by the manufacturer. First, tighten the screws normally and then check whether the engine is running smoothly or not. Then, if there is any problem, loosen the screws until the engine starts working properly.

Lawn mowers are designed to cut grass. When you turn them on, they start cutting grass. But when you stop turning them on, they stop cutting grass. So, your lawnmower is revving up and down because it's cutting grass.

How To Repair Bad Fuel in Lawnmower

1) Disconnect the ignition switch and disconnect the battery from the electrical system.

2) Remove the dirty air filter housing. Clean the dirty filter.

3) Drain the fuel tank.

4) Use a funnel to siphon gasoline from the gas tank into another container.

5) Put the lawn mower air filter back on. Reconnect the battery and connect the ignition switch. Turn the key to the "start" position and wait for the engine to start.

6) Once the engine starts, turn the key to the "run" position. The classic engine should run smoothly.

7) Close the reusable air filter cover.

How To Repair Dirty Lawnmower Air Filter

Lawnmowers use foam filters to clean air before it enters the engine manifold. Foam filters are made out of polyurethane or other chemicals. These chemicals can be harmful if you breathe them in. You should always wear protective gear when using a lawnmower.

When replacing an air filter, make sure to match the size of the old filter to the new one. Also, check the specifications of the replacement filter to ensure it fits properly.

Gas caps should be cleaned regularly to prevent them from becoming clogged with dirt or other debris. To clean a gas cap, use a wire brush and remove any debris before replacing the cap. 

How to maintain lawn mower spark plugs

Disconnect the spark plug wire carefully remove the spark plug inspect the spark plug for any cracked or a worn-out electrode if worn – replace the sparkplug with a new spark plug use the size recommended by the manufacturer. 

A carburettor idle circuit provides fuel when an engine stalls. The engine's throttle is closed by a governor. Fuel is supplied to the engine by a carburettor idle circuit. Once the engine fires, the throttle returns to full.

Cleaning your carburettor is very important. If you don't clean it, the engine will be stalled and fired repeatedly. Try these 5 steps to clean your carburettor.

How To Replace A Carburetor Float Valve

Carburettors have float valves that control the amount of fuel entering the engine. They keep the mixture at the correct level, so smoothly the engine performance.

To replace a float valve:

  1. Remove the air cleaner assembly.
  2. Remove the rubber boot covering the float chamber.
  3. Unscrew the two nuts holding the float valve in place.
  4. Pull the float valve off its mounting bracket.
  5. Carefully pull the float valve out of the hole in the float chamber.
  6. Gently wipe away any oil residue left behind.
  7. Reinstall the float valve. Screw the two nuts onto the float valve. Tighten both nuts until they feel secure.
  8. Replace the air cleaner assembly. Install the rubber boot.
  9. Attach the hose clamp to the end of the hose.
  10. Connect the hose to the filler neck.
  11. Fill the reservoir with water.
  12. Start the engine. Check the float valve for an actual leak. If there are no leaks, tighten the nut a little more.
  13. When finished, disconnect the hose from the filler neck.
  14. Dispose of the used water.
  15. Clean up all parts of the vehicle.
  16. Drive the vehicle as usual.
  17. Inspect the float valve after driving the vehicle for several miles.
  18. If there are no problems, drive the vehicle for another mile or two.
  19. Repeat step 17.
  20. Continue this process until the float valve is leaking.
  21. Use a rag to soak up the leak.
  22. Wipe the area dry.
  23. Add some WD-40 lubricant to the rag.
  24. Apply the rag to the leaky part of the float valve.
  25. Wait 10 minutes.
  26. Repeat steps 23 through 24.
  27. Repeat steps 22 through 26 until the leak stops.
  28. Dry the float valve thoroughly.
  29. Reassemble the air cleaner assembly. Attach the rubber boot.
  30. Reconnect the hose to the filler nozzle.
  31. Fill the tank unit with gasoline.
  32. Start the engine block.
  33. Drive the mower as normal.
  34. Inspect the float valve when you fill the metal gas tank.
  35. If there are no leaks after filling the tank, the float valve is working fine.
  36. If there is still a leak, repeat steps 27 through 34.
  37. If the leak persists, contact your dealer or mechanic.
  38. Always check the float valve before starting the engine.

Why Does a Lawnmower Engine Backfire?

Backfires are usually caused by a problem with the fuel system or ignition system. Gasoline with too much ethanol is dangerous because it causes problems with the carburettor gasket. Lowering the engine speed too fast can cause a misfire, leading to serious problems.

Mowing should be done in cool weather when the grass is dry. This helps prevent overheating of the engines. Also, make sure your lawnmower is clean. A dirty fuel filter could cause problems with the fuel mixture.

If you notice backfiring while mowing, stop immediately. Do not try to restart the engine. Instead, turn off the power switch on the handlebar. Then wait for the engine to cool down. Once the engine has cooled, inspect the spark plugs and wires. Make sure that none have been damaged.

If you continue to hear backfiring, contact your local service centre. They may be able to repair the problem.

Winterizing Your Lawnmower: What to Do?

Before storing your lawnmower, add a fuel stabilizer to the gas tank. Then, fill the fuel tank with gas. Run the mower engine for two minutes to circulate mixed gas throughout the engine. Fuel stabilizers will keep gas stable for years.

If you plan to store your lawnmower outside for winter, make sure it has a good-quality cover. It protects the engine and keeps snow off the lawnmower blades.

How Do You Change Oil On Lawn Mower?

Changing the oil on a lawn mower is very easy. You should make sure the engine and engine oils are cool before starting.

Read this quick 4-step guide from Briggs & Stratton to learn how to change your lawn mower's oil:

To drain the oil, turn the key to the OFF position.

Remove the dipstick. Pull the oil filler cap. Pour the used oil into a container. Replace the oil filler cap.

Turn the key to the ON position. Start the engine.

How To Prevent Lawnmower Surging?

Lawnmowers are machines used to cut grass. There are many types of lawnmowers available in the market. Some of them have more features than others. It would help if you bought a lawnmower that suits your needs.

Regularly inspect your lawn mower's air filter and clean it thoroughly when it gets dirty. Check various parts of the lawn mower regularly for proper maintenance.

Don't use low quality, bad, incompatible, and too old fuel for your mower. Make sure there isn't an issue with the gas cap like gas cap hole, and make sure the gas tank is full and the gas bowl clean.

A schedule should be made for cleaning the lawn mower spark plug carburettor. It would help if you cleaned it every time you mowed your lawn. If you don't do this, the carbon build-up inside the carburettor will increase. This will reduce performance.

Make sure your lawnmower blade is sharp. Sharp blades cut through the grass quickly. Dull blades will take longer to cut.

Keep the lawnmower away from children and pets. Children can get hurt easily if they come into contact with moving parts. Pets can also get injured if they accidentally step on the lawnmower.

Make sure you have enough space around your house to park your lawnmower. Keep the lawnmower out of the way of trees and shrubs.

Never leave your lawnmower running unattended. Always shut off the engine.

Last words

You need to know about the basic things related to lawn mowing. Nowadays, people prefer to own their lawn mowers rather than renting one. But, you need to understand all the aspects of owning a lawn mower. So, follow these tips and enjoy your lawn mower without any problems.

About the author
Written by Danica Rojero
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