Chainsaws are the go-to tool for yard work and tree cutting. It is a mechanical marvel designed to make our tasks easier and more efficient. However, as with any mechanical device, chainsaws are not immune to problems, and one of the most common issues is when a chainsaw starts and then dies.
A chainsaw that fails to run continuously can greatly hinder your productivity and cause frustration, as you constantly have to stop and try to diagnose and fix the issue. Additionally, it can also be a safety concern as you may be left in the middle of a dangerous task with a malfunctioning tool.
There are several reasons why a chainsaw might not run properly. We’ll discuss some of the most common causes and provide practical tips for fixing them.
Whether you’re an experienced user or a beginner, this guide will provide you with the information you need to get your chainsaw running smoothly again.
Why Do Chainsaws Start Then Die?
Table of Contents
Before we dive into solutions, let’s take a step back and examine the reasons why your chainsaw starts and then suddenly dies.
1. Plugged Fuel Filter
Dirty or impure fuel can clog the fuel filter inside the fuel tank, compromising its capability to efficiently sift the fuel for the carburetor. When clogged, it hinders fuel flow to the engine, causing stalling.
To prevent dirt from entering and damaging the engine, it’s crucial to regularly inspect and replace the fuel filter, if necessary. You can replace it once a year and more frequently if you’re using it heavily, especially during the winter season.
A simple switch before and after the winter can keep the engine running smoothly.
2. Dirty Air Filter
Checking the air filter before the carburetor is an easy task when it comes to determining why your chainsaw dies after starting it. Like the fuel filter, the air filter helps clean the air before reaching the carburetor.
If it’s clogged with dust, it restricts airflow, causing the carburetor to mix the wrong amount of air and fuel, eventually resulting in engine slowdown.
3. Clogged Carburetor
Your chainsaw’s carburetor is responsible for blending air and fuel into the perfect ratio. The air-fuel mixture must include enough fuel to provide a “rich” fuel mix. However, your fuel will eventually form sticky white deposits, clogging the jets in the carburetor and restricting fuel flow to the engine.
This will result in slower engine performance, and if left unaddressed, the engine could eventually stop running as the fuel supply becomes inadequate to maintain combustion.
4. High Temperature
If your chainsaw is operating sluggishly or shutting down, a vapor blockage in the fuel lines is a potential cause. Chainsaws exposed to the sun for extended durations may experience this problem when starting.
The high temperature causes the vapor pressure in the fuel lines to increase, obstructing fuel delivery to the carburetor. This results in a fuel-lean mixture, enabling the saw to start without difficulty.
However, as you increase the engine speed, the rising temperature boosts vapor pressure, decreasing the fuel supply and affecting engine revolutions per minute. The engine may stall if there’s insufficient fuel in the combustion chamber as the saw heats up.
5. Insuffiecient Compression
Chainsaws require a carefully balanced air-fuel mixture and proper compression to run smoothly. Some chainsaws with a single-piston ring in the engine may have a stalling problem.
Although the fuel and ignition systems are fine, the ring may become so degraded that the high-temperature compression is zero psi.
This can be due to thermal expansion and wear on the piston, leading to low compression and a stall when starting. If you’re experiencing this issue, it’s recommended to take your chainsaw to a trusted mechanic.
6. Faulty Ignition
The spark plug plays a crucial role in keeping your chainsaw engine running smoothly by igniting the fuel mixture. It’s critical to inspect the electrode for any signs of wear or black carbon deposits.
Over time, these deposits can degrade the quality of the spark, especially under high firing temperatures.
How to Fix A Chainsaw that Starts Then Dies?
Now that you’re familiar with the common reasons why your chainsaw is dying after you run it, it’s time to review the fixes for each problem:
1. Plugged Fuel Filter Fix
To inspect the fuel filter on your chainsaw, remove the fuel cap and decant some gasoline into a clean container. Use a thin tool like a dental pick or metal rod to clean the filter and assess its cleanliness.
If it’s clogged, replace it with a new one. If not, check for debris buildup in the carburetor and air filter.
2. Dirty Air Filter Fix
To check the air filter on your chainsaw, simply locate it on the back and loosen the bolts holding it in place with a screwdriver. Take a look at the filter to see if it’s clogged with dirt or debris.
A quick wash with soap and water should do the trick if there isn’t too much buildup. But, if it’s still not looking its best, it might be time for a replacement.
These filters are budget-friendly and should be swapped out annually to avoid engine issues.
3. Clogged Carburetor Fix
Before cleaning the congested carburetor nozzles, it’s wise to have a carburetor repair kit at your disposal. A carb cleaning spray is a helpful tool that can assist you in removing any stubborn deposits from the jets and restoring your carburetor to its optimal performance.
The initial step in cleaning your carburetor is to detach the air filter, usually found at the rear of your chainsaw. In doing so, you will be able to access the carburetor more easily.
Next, take out the bowl and clean it by simply removing both the bowl and bowl nut from the carburetor. Typically, you can find stale fuel in the bowl, so make sure to clean it thoroughly.
Finally, use the carb-cleaning liquid to clean the carburetor’s interior parts, including the bowl nut. If you see a spray exit from the other end of the jet, it indicates that any clogging has been successfully cleared.
4. High-Temperature Fix
A blocked tank vent can cause problems for your chainsaw. To fix the issue, take a look at the vents and ensure they’re not clogged with dirt or debris.
If they are clogged, open the gasoline cap for a few moments to allow the pressure to return to normal, then close it and attempt to start the chainsaw.
5. Insuffiecient Compression Fix
If your chainsaw is encountering problems after being used for a time, conducting a compression test can assist in identifying the problem. It’s recommended to perform the test when the chainsaw is at a low temperature.
To carry out the test, simply attach the gauge to the spark plug socket and pull the starter rope. Compare the pressure readings between a cold and a warm engine. If there is a substantial variance, it could indicate harm to the piston and cylinder, potentially requiring the purchase of a new chainsaw.
6. Faulty Ignition Fix
A worn-out spark plug electrode is a common issue and can be easily replaced. To diagnose this issue, try using starting fluid through the choke valve. If the engine doesn’t start or starts but then stalls, then it’s likely time for a new spark plug.
FAQs
Why does my chainsaw start but not stay running?
Your chainsaw may stop running for several reasons, such as a faulty spark plug or clogged air filter. It could be something simple like a broken fuel line or stale fuel, or the high-low adjustment screw might not be set correctly.
Other issues that are harder to fix, like a damaged carburetor or engine compression problems, could also be at play.
How do I know if my chainsaw is flooded?
If you catch a whiff of gasoline near the muffler, it’s a clear sign that your chainsaw has flooded. To diagnose the problem, remove the muffler, pull the starter cord as if starting the engine, dry the components, reassemble, and attempt to start it once more.
How long should I let a chainsaw sit if it is flooded?
Give your chainsaw a break for 15 to 20 minutes to let the fuel evaporate from the engine, then proceed with the starting steps again.
What happens if there’s too much oil in the chainsaw?
Over-oiling the chain and bar can cause debris to adhere more easily, leading to a less efficient cut and a potential safety hazard as debris is prone to flying off the chainsaw.
Should you run a chainsaw at full throttle?
The typical two-stroke chainsaw engine is meant to run smoothly at full throttle. For this reason, running at a reduced throttle speed is not recommended.
Jake is a chainsaws expert with a wealth of knowledge and experience in the field. He is a licensed professional by the National Chainsaw Program, which attests to his skills and expertise in the safe and efficient use of chainsaws.
