Lawn Mower Revs Up And Down Then Dies? [3 easy fixes]

Lawnmowers are the handiest tool to keep your backyard nice and tidy. While they ease the backyard cleaning process easier for you, they also come with their fair share of problems. One such problem is a lawn mower revs up and down then dies.

Several reasons are responsible for causing the lawn mower to surge up and down. These are as follows –

1. Clogged air filter
2. Contaminated or lack of gas or fuel
3. Faulty carburetor
4. Damaged or flawed spark plugs
5. Malfunctioning blades
6. Overheating engine

Fortunately, there are fixes to each issue involving repairs and parts replacement. Here, we will go through a detailed discussion on the causes and fixes. So, keep reading to find all the answers.

What Is a Lawn Mower Surging?

A lawn mower surging simply refers to the lawn mower’s engine revving up and down erratically with very annoying noise. Usually, the engine runs without any control during a surge.

After running uncontrollably, the engine will eventually die out and won’t start up again. It mostly happens out of some kind of malfunction in the engine.

How Does Lawn Mower Surging Occur?

The carburetor in your engine is supposed to mix air and fuel to maintain a perfect ratio of the two for necessary combustion. 

There are several routes for the fuel to pass through the carburetor. These routes are just some nozzles called jets.

When the whole operation of fuel passing through the carburetors gets disrupted for some reason, it causes the engine to stall at full throttle. 

As a result, it keeps surging up and down until the engine dies and stops. That’s how the lawn mower surging occurs over time.

Read also: Mower Deck Digging Into Ground [Causes + Fixes!]

Which Lawn mowers have surging up and down problems?

Some particular lawnmowers with engines are much more prone to surging problems.

One of the most common engines is the Briggs and Stratton lawn mower engine. Especially their classic 450, 500, and 550 models are notorious for having the surging issue due to their unique carburetor construction.

Besides Briggs and Stratton, some Honda and Kohler engines are popular for surging issues.

Troubleshooting guide for Lawn Mower Revs Up And Down Then Dies problems

Now, it’s time to dive in-depth and learn more about the reasons that can cause your lawn mower to surge up and down. 

We will discuss the common causes in-depth and provide some easy fixes to those as well. Let’s get going.

1. Clogged air filter

The air filter keeps dust and particles away from the lawn mower engine. While filtering all those elements, the air filter can easily get clogged up with dirt and debris over time. As a result, it can’t ensure the free flow of air into the engine.

Without enough air flowing into the engine, it ends up with only gas or fuel inside the engine, and the air-to-fuel ratio gets messed up. 

This causes combustion failure in your engine, and your lawn mower goes into the surging cycle.

Potential fix:

There are two fixes to this problem. First, you can try cleaning the air filter to unblock it or replace it with a new one. Here’s how to clean the clogged air filter in your lawn mower –

• Step-1: First, locate where your air filter is installed and remove the cover.

• Step-2: Then, remove any connection with the air filter you may have in the lawn mower.

• Step-3: Take out the filter and clean all the heavy dirt stuck on the filter.

• Step-4: Now, use a dishwashing liquid and water to wash the filter to remove all the dirt and debris.

• Step-5: After washing the filter, dry it under the sun.

• Step-6: Once it dries completely, put some engine oil on the filter. Let the filter soak in the oil properly.

*To avoid mess, place the filter in a plastic bag, fill it with oil, and squeeze the filter inside to mix the oil.

• Step-7: Before putting the air filter back into the housing, clean the housing and any fitting on it.

• Step-8: Finally, re-install the filter, reconnect all the plugs and wires, and put the cover back on.

2. Contaminated or lack of gas/fuel

Another common reason for your lawn mower surging up and down is the lack of fuel. When there is not enough fuel in your engine fuel tank, it can’t start up the engine properly and results in only revving up and down.

Also, bad or dirty gas can cause the same thing to happen. If the fuel has been in the engine for over 3 months, it might go stale. 

This can reduce the combustion properties of the gas and cause the mower to surge up and down.

Potential fix:

Well, this problem has a very easy fix: putting some new fuel or gas into your fuel tank. Here’s how you can do it –

•  Step-1: Open the fuel tank cap and check the fuel level and quality. Bad fuel usually has a sweet smell to it.

• Step-2: To remove the fuel from the tank, you can tip the mower on one side and drain all the fuel into a container.

•  Step-3: If you have a removable fuel line, you can also unplug the fuel line to drain the fuel out of the tank.

• Step-4: Take off the gas cap, and check if the fuel tank is empty.

•  Step-5: After draining all the fuel from the tank, you must put new gas inside the tank according to your lawn mower’s requirements.

Watch this YouTube videos for more details: https://youtu.be/8YRkMgYwhhk

3. Carburetor problems

Carburetor is the key component playing a role in lawn mower surging. Several nozzles or jets running through the carburetor can get clogged sometimes. When that happens, fuel and air can’t pass properly, resulting in combustion failure.

Other than that, any damage to the carburetor can also cause this problem. For instance, a dirty carburetor or leaking carburetor gasket can result in the carburetor malfunction and cause your lawn mower to surge up and down.

Potential fix:

If you have a damaged carburetor or a leaking gasket, you must replace the parts. But cleaning the carburetor can fix the issue of a clogged jet or dirty carburetor. Check out how you can clean it –

 Step-1: First, remove the fuel tank on your lawn mower.

Step-2: Next up, take a wrench and loosen up the main jet on the carburetor. Some gas may start dripping while doing so.

Step-3: Now, take the jet and remove any kind of debris or dirt stuck on it and clear any clog it may have.

Step-4: Use a carb cleaner or a brush to clean the jet properly.

Step-5: After that, take off the carburetor bowl and clean it. Replacing it with a new carb bowl is better if it’s beyond cleaning.

Step-6: Re-install the carburetor bowl and the main jet. Then, tighten the jet and secure it.

Step-7: Finally, put the fuel tank back in place and reconnect the fuel line to finish cleaning.

Check out the following video for a complete guide if you want to clean the whole carburetor.

Ways To Prevent The Lawn Mower From Surging

Here’s some good news: if you maintain your lawn mower properly, you can easily avoid this surging issue. Go through the following tips to avoid the problem –

• Never let bad gas or fuel sit in the fuel tank long.
• Try to clean the air filter every once in a while.
• Avoid using low-quality gas on the lawn mower.
• Always follow a regular cleaning and maintenance session.
• Check the gas cap every time after use, and close it properly.
• Keep an eye out for the spark plug issues.

Read also: John Deree Mower Deck Stuck In Up Position

people also ask

Let’s get through some interesting questions many people ask regarding the Lawn Mower Revs Up And Down Then Dies. They might help you understand and learn a bit more about the problem.