Lawn Mower Starts Then Dies? (Possible Causes & Fixes)

Lawn Mower Starts Then Dies

A good lawnmower can make taking care of your yard a breeze. However, even the best lawnmowers won’t always work the way they’re supposed to.

If your lawnmower starts then dies, it could be because of a dirty carburetor or malfunctioning spark plug. The issue could also be related to your engine or coming from a clogged air filter. That being said, carburetor issues are the most likely cause of this problem, so be sure to check that first.

Given how many problems could be causing your lawnmower to start then die, it’s worth taking some time to research the issue before trying a repair. Below, you’ll find all of the information that you need to know in order to fix this issue.

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Why Does My Lawn Mower Start Then Die?

Carburetor Problems

The most likely cause of this issue is a problem with your lawnmower’s carburetor. Every gas-powered engine is equipped with a carburetor. Its purpose is to mix gas and air within the engine and regulate them so that they exist in the proper quantities.

If your lawnmower is starting then dying, it could be because you have a loose carburetor. This won’t allow your engine to function properly because it won’t be getting enough gas to do so. 

Fixing this problem is relatively easy. All you need to do is power your lawnmower off and then try tightening the carburetor.

It’s also possible that your carburetor’s bowl has clogged. Carburetors have a bowl underneath them that attaches to the engine with a screw. This sometimes get clogged and prevents air from being able to move freely about the engine.

If you’ve had your lawnmower for years, then you may also need to consider the possibility that your carburetor has simply worn out. Carburetors are one of the first parts of your lawnmower that need to be replaced. If all else fails, then replacing your carburetor entirely maybe your best option.

Old Gas That Formed Residue

This may be the source of your problem if you’ve had the same gas in your lawnmower’s engine for a long time. Extended periods of non-use can cause your lawnmower’s gas to evaporate partially. This process leaves behind particles that can turn into residues.

These residues, in turn, may clog the internal parts of your carburetor and restrict the flow of gas that your engine receives. You might be able to fix this problem by draining out the old gas and putting in new fuel along with a fuel stabilizer.

Defective Spark Plug

It’s also possible that your spark plug is the source of this problem. Spark plugs can sometimes have carbon build up inside their socket. This can weaken the spark that it’s able to produce and affect how your lawnmower’s engine functions.

Too Much Oil

You may also be having this issue because you’ve overfilled your lawnmower’s oil reservoir. The main sign of this is white smoke coming out of your engine as it stalls.

Blocked Gasoline Cap

Finally, sometimes this issue can be traced back to a blocked gasoline cap. Most gas caps have holes in them that are meant to stabilize the air pressure that exists in the tank. 

When this hole gets blocked, it can create a vacuum in the tank that disrupts the flow of gas to the engine’s carburetor. You may be able to fix this by simply clean the hole in the cap or replacing the cap with a new one.

How Do You Fix a Lawn Mower That Starts Then Dies?

The steps you need to take to fix this issue will vary based on what’s causing your lawnmower to die after starting. Here’s an overview of what you can do to fix each of these potential causes.

Clogged Carburetor

Clogged carburetors are typically the result of fuel that’s been left in the lawnmower for too long. As discussed above, clogs often occur when gas evaporates and leaves behind a residue. You may be able to fix a clogged carburetor with a carburetor cleaner. If that doesn’t work, you might have to replace this part of your lawnmower’s engine entirely.

Fuel Cap Vent

If you’ve traced your issue back to the lawnmower’s fuel cap, then your fix should be fairly straightforward. You should try to loosen the fuel cap slightly and see if that allows the engine to run normally.

If this works, then it’s a sign that the fuel cap’s vent is clogged. You will need to either fix this clog or replace the cap in order to fix the problem.

Spark Plug Issues

You should start by inspecting your lawnmower’s spark plugs for signs of wear and damage. You may find that the insulator is cracked or that an electrode has been damaged or burned away. In these scenarios, you’re going to have to replace the entire spark plug.

You may also want to use a spark plug tester to get a better understanding of where the problem is originating. When using this, you should be able to see a good spark between the tester’s terminals. If you don’t, that’s another sign that you need to replace your lawnmower’s spark plug.

How Do You Replace a Lawn Mower Carburetor?

As you work to resolve this problem, you may find that your lawnmower’s carburetor is beyond the point of repair. In that situation, you’re going to need to replace the carburetor entirely before your mower will work again.

Fixing this isn’t overly complicated. It’s a task that most experienced DIYers will be able to complete without too many issues. To do so, you’ll first want to gather the following tools:

  • Nut driver set
  • Pliers
  • Shop rag
  • Fuel safe container
  • Work gloves

Once you’ve got these tools and a new carburetor nearby, you’re ready to get started. Here’s a step-by-step guide on how to get the job done.

  1. Disconnect the spark plug wire.
  2. Remove the air filter housing. You’ll have to start by taking the cover off. Then, take out the air filter and remove the screws from its base. Finish by releasing the breather tube and pulling off the base entirely.
  3. Drain the fuel tank. You’ll want to place a shop rag under the fuel tank while you do this to catch any spills that may occur.
  4. Remove the blower housing. To do this, you’ll need to release the starter rope from the mower handle. Then, remove the screws from the blower housing and pull it off the engine.
  5. Remove the carburetor. Separate the mounting bracket arms to release the carburetor from its adapter.
  6. Install the new carburetor. Start by installing the new O-ring. Then, connect the fuel line to the new carburetor and secure it with the spring clamp. Finish by connecting the governor and choke linkage rods, pushing the carburetor into the bracket arms, and attaching them.

Is it Worth Repairing a Lawn Mower?

As you look through all of the steps that you’ll have to take in order to repair your lawnmower, you may start to question whether doing so is actually worth it. The answer to this question depends on the specific part of your lawnmower that isn’t working and how much time you’re willing to invest in fixing it.

Generally speaking, carburetor issues are both easy and cheap enough to repair that they’re worth doing so. You can buy a new carburetor for your lawnmower for under $100 and can install it yourself.

Similarly, issues with your lawnmower’s spark plugs are also cost-effective to repair. You would probably even be able to hire a professional to fix a spark plug issue for you at a lower cost than what you would pay for a new mower.

The calculus for this question becomes different if you’re having more severe engine issues. Internal engine damage can cost anywhere from $750 to $2,000 to repair. At this price point, it just makes sense to invest in a new lawnmower. Especially when you can buy a new one for as little as $150.

How Many Years Should a Lawn Mower Last?

You may also be thinking about purchasing a new lawnmower if you’ve had your current machine for a long time. However, lawnmowers can last longer than you might expect. Even if you’ve had the same one for 5 or more years, it may still not be time to replace it.

The average life expectancy of a lawnmower is between eight and ten years. You can extend your unit’s lifespan by taking good care of it. Performing simple maintenance steps like changing the oil filter and emptying unused fuel can add up to make a big difference.

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Related Questions

How often should you have your lawnmower serviced?

Most experts recommend having your lawnmower serviced every 50 hours or so of use. Or, if you don’t spend that much time using your lawnmower in a single year, it’s worth having it looked at annually just to be safe.

Does Home Depot do lawnmower repair?

Yes, Home Depot does have lawnmower repair services that you can use. The company says that it’s happy to repair your lawnmower no matter what brand it is or where you purchased it from. They also offer a 90-day service warranty.

How do I know if my lawnmower carburetor is bad?

One of the main signs of a bad carburetor is a lawnmower that starts then dies. However, this isn’t the only sign that it may be time to replace your carburetor.

Other signs include an engine that runs either lean or rich. Essentially, this means that the balance between fuel and air (which the carburetor is supposed to regulate) is off. It may be time for a carburetor replacement if this is happening to your lawnmower.

Kellan Jansen

Kellan is a content writer who specializes in everything DIY. When he's not behind the keyboard, he enjoys spending time with his pets, playing music, and geeking out about basketball. He hopes to make your home improvement projects a little bit easier to accomplish.

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