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Craftsman Weed Eater Won’t Stay Running (Common Causes & Easy Solutions)

by Jack Grover
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Experiencing issues with your Craftsman weed eater not staying running? You’re not alone!

person using weed eaterr

One common cause for this problem is dirty fuel components, which can lead to a thick, sticky residue clogging various parts of the device. However, there are several other reasons why a weed eater might run unevenly or stop altogether. 

In this article, we explore the most common causes and easy solutions to get your Craftsman weed eater back up and running smoothly. To get the most out of this guide, we recommend reading it from top to bottom without skipping any sections.

So, let’s dive in and discover what could be causing your weed eater to malfunction — and how to fix it quickly and efficiently.

Craftsman Weed Eater Won’t Stay Running

There are several reasons why a Craftsman battery weed eater might struggle to stay running:

Some of the issues you’re most likely to face include old fuel, a clogged fuel filter, and a dirty carburetor. The great news is that these problems can often be resolved with some simple maintenance and troubleshooting!

Here is a quick breakdown of the most common causes and their respective solitons:

Old fuelRefill with new fuel
Clogged fuel filterClean or replace
Spark arrestor, muffler & exhaust port issueRemove carbon build-up
Improper gas supplyReplacing supply tank
Dirty carburetorDeep-clean or replace

In the following sections, we delve deeper into these common issues and further explore other potential causes for your weed eater’s performance problems.

By understanding the various factors that may be affecting your device, you’ll all the information you need to get your weed eater back on track!

Old Fuel

One of the most common issues with petrol weed eaters is related to fuel. Petrol fuel stays stable and useful for about 6 months after you purchase it.

A machine can stop working if it runs out of fuel or if the fuel has been left sitting in the weed eater for several months during storage. Old fuel doesn’t properly flow to every part of the engine; instead, it creates friction and stops the functions.

Additionally, contaminated fuel containing water can cause operational problems.

Another thing to be mindful of is that two-stroke engines, which are commonly found in weed eaters, require a specific mixture of petrol and oil to function correctly. Incorrect ratios can lead to poor performance or even complete failure of the device.


To address these fuel-related issues, follow these steps:

  1. Before every use, check the fuel tank and ensure that there is sufficient fuel for your task.
  2. If the fuel has been left in the weed eater for an extended period or appears contaminated, replace it with a fresh mixture. We strongly recommend using ethanol-free new fuel for your weed eater.
  3. Make sure to use clean petrol and oil mixed in the correct ratio as specified by the manufacturer.

If you continue to experience issues after checking your fuel supply, consider consulting a professional for further assistance.

Fuel Filter Issues

Using less-optimal fuel (the wrong fuel ratio or having old fuel for a long time) in your weed eater can cause problems with the fuel filter — e.g., clogging up for sticky carbon residue.

If your device starts fine but dies when throttled, this often indicates restricted fuel flow. A clogged fuel filter allows only a small amount of fuel to pass through, which is sufficient for starting and idling but not enough to maintain higher revs.


To address this issue, it’s essential to check the fuel filter and clean it thoroughly, paying close attention to all the sticky substances. In some cases, it might be more effective to replace the filter altogether, especially since they are relatively inexpensive.

When mixing fuel for a two-stroke engine, ensure that the oil used hasn’t gone bad — contrary to popular belief, two-stroke oil does have a limited shelf life.

Side Note: Air Filter

Once the fuel has passed through the fuel filter, it enters the carburetor, where it mixes with air. If your air filter is clogged, it can suffocate the engine when you throttle, causing performance issues.

A Craftsman 25cc weed eater may struggle to stay running due to debris buildup on the air filter, often resulting from old fuel. Thus, before installing the fuel filter back, make sure to check the air filter as well.

To access the air filter, you’ll typically need to turn a plastic knob or unscrew a single screw, depending on your weed eater model. Once you’ve gained access, clean or replace the filter as necessary.

Air filters are generally inexpensive, so replacing them when needed is a cost-effective solution for maintaining optimal performance in the long run.

If you’re unsure about performing these tasks yourself or find them challenging, don’t hesitate to seek professional help for the best results.

Spark Arrestor, Muffler & Exhaust Port

The spark arrestor, muffler, and exhaust port are three critical components that can impact the performance of your Craftsman weed eater. Without them functioning correctly, your weed eater may struggle to stay on.

Spark Arrestor

The spark arrestor plays a crucial role in preventing the engine from discharging sparks. Over time, it can become clogged with soot, causing the engine to stall.

  1. Ensure there is an appropriate gap in the spark plug.
  2. Inspect the piston for carbon buildup. Often, this buildup appears as crusty dirt on top of the piston.
  3. Gently remove any debris you find and replace the piston if it appears worn out. Remove and clean the spark arrestor with a wire brush or replace it if necessary.


The muffler helps remove hot ignited gases from the engine, keeping it cool and ensuring combustion can continue. However, the carbon build-up can clog the muffler over time, preventing heat from escaping and stopping the engine.


Remove and replace the arrester screen within the muffler.

Alternatively, you can clean it by heating it to red hot with a blow torch to burn off any build-up. Once cool, use a soft cloth to remove any remaining dirt.

Remember to wear protective gear while performing this task.


Often overlooked, a clogged exhaust can also cause issues with your Craftsman weed eater’s performance. While we tend to focus on fuel and air intake, it’s essential not to forget the possibility that the problem may lie with air exiting the device.


Remove any debris you can find during the inspection. Look out for clogged or worn-out portions in the exhaust port.

If you’re unsure about handling these tasks yourself or find them too time-consuming, seeking professional assistance is always an excellent option.

Improper Gas Supply

An improper gas supply can significantly impact the performance of your weed eater. A Craftsman 4-cycle weed eater, for example, relies on a consistent gas supply to keep its engine running smoothly.

Issues with the gas supply can arise due to clogged components or leaks in the gas tank.

Clogged components may restrict the flow of gas to the engine, resulting in poor performance or even complete failure.


It’s essential to inspect and clean your weed eater’s fuel system regularly to ensure that all parts are functioning correctly and free from debris.

Gas tank leaks, on the other hand, can cause not only performance issues but also potential safety hazards. If you suspect a leak in your weed eater’s gas tank, it’s crucial to address this issue promptly.


Attempting to repair the tank yourself might not be feasible or safe; therefore, it is highly recommended to replace the entire tank with a new one.

Regular maintenance and inspections will help prevent these problems from occurring in the first place and prolong the life of your device.


The carburetor is a vital component in gasoline engines, ensuring that air and fuel work together to start a combustion engine. It can also be one of the most challenging parts to troubleshoot in small engines.

As it is closer to the fuel inlet, it can mostly have formed a clog over time. A clogged carburetor can cause a weed eater to die when you pull on the throttle.

Before diving into technical steps, ensure that your carburetor isn’t clogged. Here is how you go about it:

  1. Remove the carburetor and look for the dirt build-up.
  2. Always clean with a carb cleaner. There are plenty of carburetor cleaning options on the market, such as SeaFoam motor treatment.
  3. Ensure proper cleaning in each part, or else your Craftsman weed eater won’t stay running
  4. Always stay alert while using the carb cleaner. You should wear eye protection as it would cause bad irritation to your eyes.

Now, let’s examine the areas of your carburetor which are common culprits when a weed eater starts but stalls when throttling:

Idle Speed

Adjusting the idle speed of your weed eater might seem intimidating at first, but it’s relatively simple and typically only requires a screwdriver.

Before starting, consider purchasing a carburetor rebuild kit.

To test the current idle speed, locate the adjustment screw (usually behind the air filter), and adjust it using only ¼ turns before trying to start the trimmer again.

If the weed eater starts without issue and stays on while revving the throttle, you’ve fixed the problem.


Inside one side of the carburetor lies a diaphragm — a small plastic piece with flaps. If these flaps are bent or worn out, replace them using a diaphragm repair kit specified in your user manual.

Replace the diaphragm by placing it flat in the small recess of the carburetor and reassemble the device with the screws you removed earlier.

Metering Diaphragm

On the opposite side of the carburetor, there’s another set of screws. Unscrew them to assess the condition of the metering diaphragm, which helps regulate engine speed.

If you find it worn out or even worn through entirely, replace it before reassembling the carburetor and testing your weed eater.

By addressing issues with the idle speed, diaphragm, and metering diaphragm, you can help ensure that your carburetor functions correctly and maintains optimal performance for your Craftsman weed eater.

Here’s a tutorial on fixing Craftsman weed eater you may find helpful:


Why does my weed eater keep turning off?

There are several possible reasons why your weed eater keeps turning off. These issues could be related to the fuel line, exhaust, or air intake.

However, one of the most common causes is a faulty or clogged fuel filter.

Fuel filters can become clogged when fuel sits in the tank for an extended period without being changed. While most of the fuel evaporates over time, some of it forms a thick residue that obstructs the flow of fuel within the device. This blockage can lead to your weed eater shutting off unexpectedly and frequently.

To keep your weed eater running smoothly, it’s essential to address these potential issues. Regularly inspect and clean or replace your fuel filter to prevent clogs from forming

Additionally, ensure that your fuel line, exhaust, and air intake are in good working order by performing routine maintenance checks.

What to do when a weed eater won’t start?

If your weed eater won’t start, it’s essential to identify and address the root cause of the issue.

Here are some steps you can take to troubleshoot and resolve the problem:

  • Check the fuel. One common reason for a non-starting weed eater is old or contaminated fuel. Try using ethanol-free premix fuel to ensure that your device has a clean and appropriate fuel source.
  • Clean or replace the carburetor. A dirty or damaged carburetor could also be preventing your weed eater from starting. Inspect the carburetor for any debris or damage, and clean it thoroughly if necessary. If the carburetor appears to be damaged beyond repair, consider replacing it.
  • Consult a professional. If you’ve tried these steps and your weed eater still won’t start, it may be time to seek professional help. A skilled technician can diagnose and repair more complex issues that may be affecting your device’s performance.

Regular maintenance and timely repairs will help ensure that your device continues to operate efficiently for years to come.

Why does weed eater stall?

A weed eater may stall due to various clogged components:

  • Spark arrestor. Over time, dirt and debris can build up on the spark arrestor, especially in older weed eaters. A clogged spark arrestor can restrict airflow and cause the device to stall.
  • Carburetor. Dirt and debris can accumulate over time, obstructing the flow of fuel and air mixture necessary for combustion.
  • Fuel and air filters. Blocked filters can prevent the proper flow of fuel or air to the engine, causing it to stall during operation.

To prevent your weed eater from stalling, regularly inspect and clean these components as part of routine maintenance. Keeping your device clean and free from debris will help ensure optimal performance and reduce the likelihood of stalling issues.

If you continue to experience problems with your weed eater after addressing these potential causes, consider consulting a professional for further assistance.


As you can see, there are several potential reasons why a Craftsman weed eater might not stay running. It’s essential to thoroughly examine all the possible causes and address each one accordingly before assuming that your device is beyond repair.

Regular maintenance and timely troubleshooting can help prevent many of these issues from occurring in the first place. However, if you continue to experience problems with your weed eater after attempting to resolve them yourself, it’s always a good idea to consult a professional for further assistance.

By staying proactive in the care and upkeep of your Craftsman weed eater, you can ensure its longevity and sustained performance for years to come.

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