Mission: Starting a Flooded Chainsaw
One of my youngest memories is being with my father in an orchard out of the city cutting trees for firewood.
When we were done, the car, stacked up with firewood, wouldn't start.
We had to wait for what felt like forever for my mum to turn up to take me home while Dad tended to the car.
And what does that have to do with starting flooded chainsaw engines?
Nothing, except to say my dad was pretty handy with a chainsaw. He had a green Poulan and as a kid, it just seemed the coolest thing in the world.
Anyways, enough of this chit chat – let's get to it.
The Pre-Mission Briefing: What You Need to Know
Before we get into it, make sure you have fresh petrol in your engine.
If you've got an old mixture of oil and gas that's older than a month, it will be harder for your engine to start.
We suggest you drain and add fresh petrol to ensure a good start. ⛽
If you have tried several times unsuccessfully to start your unit, it is most likely flooded, especially so if you can smell gas.
Flooded means there is excessive fuel pumped into the engine, which has displaced the vital ingredient of oxygen for starting.
Do not prime the engine again as you will add to the problem!
There are two ways you can try to clear the unit of the excess fuel and get it chopping wood.
Phase 1: The Waiting Game ⏱️
The first is the easiest and most common method. Let your chainsaw sit for 15–20 minutes to allow the fuel to evaporate from the engine, and then repeat the starting instructions.
This method will work best with a mildly flooded engine. The same principles apply to lawnmowers and weed whackers.
Phase 2: The Hands-On Approach ๐ ️
For a more stubborn flood, your mission is to manually clear the engine.
Here's your checklist:
- To ensure your safety before you begin, make sure the chain brake is fully engaged.
- Move the choke lever to the 'off' or 'run' position, as adding more fuel is the opposite of what you want to do.
- Set the saw to fast idle, which is often done by engaging the throttle lock or by pulling the choke out and pushing it back in.
- Double-check that the on/off switch is in the 'on' position so the engine can get a spark.
- For a stable and safe start, place the chainsaw firmly on the ground, get a secure grip on the handle, and pull the starter rope with several short, sharp motions.
If the engine doesn't fire after 15 pulls, the spark plug may be 'wet fouled'.
In this case, remove the spark plug and inspect it for wet, oily deposits.
While the plug is out, turn the saw upside down and pull the starter a few times to eject any excess fuel through the spark plug hole.
Use a lighter or torch (carefully and away from fuel!) to gently dry the spark plug tip, or replace it if it’s old or damaged. A good spark plug makes a big difference on cold starts.
Once the plug is re-installed, prime the carburetor. If your chainsaw has a primer bulb, press it 3–6 times until you see fuel moving through the line.
Now start your machine using the normal procedure. Put the choke on, pull to pop, then turn the choke off and fire it up.
The Intel: Why Chainsaws Flood So Easily
Chainsaw carburetors are finicky. A rich air-fuel mix helps cold-start a 2-stroke engine, but too much fuel and not enough spark or oxygen will choke it out.
This is especially common when:
- If you are using a new saw, you might accidentally apply the choke for too long, which is a common cause of flooding.
- Repeatedly trying to start the engine without it firing can pump excess fuel into the carburetor.
- In cold weather, the fuel can become thicker, making it harder to ignite and leading to an accumulation in the engine.
- A clogged or dirty air filter restricts airflow, which disrupts the fuel-to-air ratio and can easily cause flooding.
Always follow your chainsaw’s specific startup sequence.
Each model is a little different.
Reading the manual, even just once, pays off.
The Prevention Protocol: Stop Flooding Before It Starts
- To prevent starting issues, always fill your saw with a fresh fuel mixture that is less than a month old, and consider adding a fuel stabilizer if you plan on storing it.
- Get into the habit of only pressing the primer bulb the number of times recommended in your user manual, as over-priming is a direct cause of flooding.
- Learn the correct starting procedure for your specific model so you know exactly when to switch from a full choke to a half choke.
- Before you start your work, perform a quick check to ensure your air filter is clean and your spark plug is in good condition for a reliable ignition.
- When you pull the starter cord, use a quick and decisive motion because slow or hesitant pulls will not be strong enough to properly ignite the fuel.
Visual Recon: Watch a Pro Do It
Advanced Ops: Master Your Machine
- Improve your cutting performance by learning the correct angles and file sizes required to properly sharpen your chainsaw's chain. You can learn more at How to sharpen a chainsaw.
- Increase your safety by understanding the kickback zone on your guide bar and practicing proper handling techniques to always stay in control. See our guide on how to reduce the chance of chainsaw kickbacks.
- Refine your technique with our guide on correct body positioning and saw movement, which will help you make more accurate and safer cuts.
- Extend the life of your equipment by following the four essential rules of chain maintenance, covering everything from cleaning to proper tensioning.