If you’ve ever lived in a wooded area, you probably know how tree limbs or even full trees can fall and block an entrance or exit. Nothing is worse than when you take out your chainsaw, try to start it up, and gas flies out of the muffler.
Gas in your muffler is a sign that it’s escaping its storage or delivery system or is not being used completely in the engine. Check for holes in your gas tank or fuel link, and avoid flooding the engine. Engage the chain brake to let excess gas out, and replace the spark plug if necessary.
With many small engine machines, troubleshooting gas leaks can be difficult. Read on to learn more about the reasons why your chainsaw muffler is full of gas and how you can solve issues with fuel delivery and fuel usage and get your chainsaw up and running.
Fuel Storage and Delivery Issues in a Chainsaw
One challenge that comes with any type of combustion engine is that it takes a lot of specific conditions to work correctly. While these engines are fairly reliable, sometimes a small issue that can be easily fixed can create serious symptoms.
Combustion engines work by creating a small series of explosions that moves through a series of positions to power your device (source). Pressurized gas is placed into a small chamber, and then a spark is issued to this gasoline.
When the gas ignites quickly from the spark, it changes the pressure in the system, moving a piston. When this piston moves, it creates energy that powers your device. If something goes wrong in this process, the engine won’t work.
One issue that can often occur with this system is that the gas won’t get pushed all the way through the engine. Perhaps you have a small hole in the gas tank or have a hole, scratch, or loose connection with your fuel line (source).
If the gas leaks somewhere in the storage or delivery system, then it might interrupt other parts of the device.
If your muffler is full of gas and is spitting it out with the exhaust, you could have a leak that is causing the gas to get mixed into the exhaust system. The muffler is used as part of the exhaust system to reduce noise, so if you find your muffler is full of gas, the exhaust system is taking in gasoline from somewhere (source).
To fix the issue, check that your gas tank and fuel lines don’t have a leak. If you can’t find a leak, that means there is an issue with the fuel’s usage within the combustion system itself.
Too Much Gas in the Engine
Another potential cause for a muffler full of gas is too much gas being pushed through the engine. This is called “flooding” the engine (source).
Engines really don’t use much exterior power to work. Aside from starting the engine, no exterior energy is needed to keep the system running, and it powers itself.
However, some sort of energy is required to start the engine. The gas needs to be ignited, and gas needs to actually be pulled into the chamber to ignite. This is why many devices, including chainsaws, use a primer (source).
On most chainsaws, there is a small bulb full of gasoline that you normally push two or three times before starting your chainsaw. This is to help actually deliver the fuel into the engine so that the engine can start.
However, if you push the bulb too many times, you can force too much gas into the system, thus flooding it. Another potential cause of the flooding is that the engine did not ignite on its first attempt to start, so it pumped more gas into the system with the old gas still lingering.
Sometimes, engines become so flooded that the gas is forced to escape the engine and flow into the exhaust system. If this occurs, your chainsaw muffle might fill with gas.
To fix this, simply lay the chainsaw on the ground and engage the chain brake. This process will let the gas leak out (source) and prevent more gas from flowing into the muffler.
Gas Not Burning in the Engine
The other potential reason your chainsaw’s muffler might be full of gas is that gas might not be burning completely (or even at all), causing it to escape into the exhaust system. After the gas burns, the carbon dioxide must escape. This is why the exhaust system exists.
However, let’s say that for whatever reason, the gas did not burn in the engine or did not burn completely. The leftover gas then builds up and floods into the exhaust system.
However, it is important to note that while flooding might be a cause, you might also have an issue with the engine itself.
The most common issue associated with this is that the spark plug is not working correctly. Spark plugs typically only last for two or three years, so if your chainsaw is older than this, you might need to replace your spark plug (source). Additionally, the battery powering your spark plug might be dead, causing your engine not to start and the spark plug not to ignite.
If you find gas in the chainsaw muffler and you expect it is due to gas not igniting, allow the gas to drain and replace your spark plug or battery.
And while you’re at it, remember to clean the muffler, especially the silencer part, as it might get really dirty and potentially clogged up from all the gas. I have a detailed guide on cleaning a chainsaw muffler silencer that you can follow to help you out.
Final Thoughts
Finding gas in your chainsaw’s muffler and exhaust system is almost always a sign of a leak in the fuel delivery system or the gas is not burning correctly. Ensure your fuel lines are not damaged and properly connected, and see if your spark plug is working correctly. All of these issues can cause gas to flow into the muffler.
If none of these suggestions fix the issue, take your chainsaw to a small engine mechanic.