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How to Start a Flooded Chainsaw [Unflood and Clear Your Saw Engine!]

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A failing chainsaw is the last thing you need when cutting timber or clearing tree litter. And if your chainsaw fails to fire up, there’s a good chance it’s flooded. But – how do you start a flooded chainsaw? And how do you unflood it?

Well – the good news is that unflooding a chainsaw is easy! We’ve seen many flooded chainsaws since flooding is a common cause of chainsaw failure. It’s usually due to incorrect starting procedures, and a wet sparkplug is likely the biggest culprit.

We have a ton of experience unflooding chainsaws and operating them faithfully. We also want to share how to unflood your chainsaw without stress. And how to prevent it from reoccurring!

Sound good?

Then let’s get started!

How to Start a Flooded Chainsaw

To start a flooded chainsaw, make sure the choke is off. Hold the throttle wide open and pull the starter cord as many as 20 times. With the control lever in the idle position and the throttle wide open, a lean fuel mixture will rectify the air-to-fuel ratio in the cylinder, allowing easy starting.

A flooded chainsaw can get diagnosed by removing the spark plug for inspection. Are the electrodes on the spark plug wet? Then the engine is flooded.

Here’s how to fix it.

  • Ensure the engine switch is OFF.
  • With the spark plugs removed and the spark plug cable out of the way, turn the chainsaw upside down and pull the starter cord a few times to purge the cylinder of all gas.
  • Wash the spark plug in a solvent.
  • Dry the spark plug with a lint-free rag or compressed air. 
  • Refit the spark plug and cable.  
  • Make sure the choke is OFF. 
  • With the chainsaw in the RUN, IDLE, or Warm Start position (depending on your chainsaw model), open the throttle to its full extent and pull the starter cord until the engine sputters into life.
holding and examining a wet sparkplug from a flooded chainsaw
How to start a flooded chainsaw? Step one is to double-check and clean the spark plug! A wet chainsaw spark plug is arguably the single most common issue that causes a flooded gas chainsaw. Once you clean and dry your spark plug, use the correct starting procedure and try to start the saw from the proper position.

What Happens When You Flood a Chainsaw?

A flooded chainsaw won’t start due to a too-rich air-to-fuel mixture entering the cylinder and wetting the spark plug electrodes, preventing the spark plug from igniting the fuel vapor. Attempting to fire a chainsaw repeatedly with excessive use of the choke is the most common cause of flooding.

The chainsaw choke is the chief culprit in the flooding problem. 

  • The choke limits air intake into the carburetor, creating a fuel-heavy air/fuel mixture (aka a rich mix) with insufficient oxygen to combust effectively.
  • An overly rich fuel mixture douses the firepower of the spark plug electrodes and prevents the engine from starting. 
  • Trying to restart a warm chainsaw engine (+60 seconds running time) with the choke on causes flooding.

How Long Does It Take for a Flooded Chainsaw to Start?

It is possible to restart a flooded chainsaw by letting it stand for several hours or overnight, allowing the fuel mixture in the cylinder to evaporate. A flooded chainsaw can unflood in less than six hours in hot weather.

You can unflood your chainsaw in a matter of minutes by:

  • Remove the spark plug and expel the fuel mix by pulling the starter cord repeatedly, refitting the plug, and starting the engine with several pulls on the starter cord with the choke OFF.
  • Pull the starter cord repeatedly with the master control lever in Idle or Warm Start mode.

Note: Two-stroke oil will remain in the engine after the gas has evaporated, which may prolong the unflooding procedure.   

getting ready to start a chainsaw mower with manual starter handle
Here’s our simple chain saw troubleshooting routine. Check the chainsaw power switch first. And always start your chainsaw according to the official starting procedure in the owner’s manual. If the saw still won’t start? Then double-check the gas tank to ensure adequate fuel and proper fuel flow. If there’s gas and the chainsaw still won’t start, we begin to fear a chainsaw flooding issue. Saw floods usually involve a faulty, dirty, or wet spark plug. So, grab a paper towel and check your spark plug. After drying your spark plug, you can try starting the chainsaw – hopefully, this time without flooding. (A few more last-ditch ideas to double-check include the spark plug wire and the carburetor adjustment.)

How Do You Start a Stihl Chainsaw When it’s Flooded?

To start a flooded Stihl chainsaw, put the chain brake on, turn the engine START switch ON, set the carburetor to the IDLE position on the control lever, open the throttle as wide as it can go, and pull the start cord several times until the engine fires up.

If your Stihl chainsaw doesn’t start after that procedure, remove the spark plug and actively unflood the cylinder.

How to fix a flooded STIHL Chainsaw Engine

Read More!

How Long Does It Take for a Stihl Chainsaw to Unflood?

Leaving a Stihl chainsaw idling overnight will unflood the cylinder via evaporation of excessive fuel. Leaving the chainsaw to stand in the sun for a few hours will make starting easier. A Stihl chainsaw can unflood in a few minutes by actively clearing the cylinder of fuel.

chainsaw motor oil and gasoline cannister resting on a tree stump
Regular chainsaw maintenance is the best way to prevent chainsaw malfunction. A clean air filter and spark plug can help your chainsaw start and run like a dream. We usually check our spark plug and air filter every 10 hours of cutting. Use a flashlight to examine the sparkplug. Check for wear and tear – and remove any soot or gunk with a clean towel.

How Do You Clear a Flooded Chainsaw Engine?

A flooded chainsaw can get cleared by pulling the start cord several times with the START switch ON and the choke OFF to allow more air into the cylinder. Or by turning the Start switch OFF and removing the spark plug to drain fuel from the cylinder.

  • Remember: Attempting to start a chainsaw with the Start switch OFF and the choke ON will flood the engine.

What Else Causes a Chainsaw to Flood?

A chainsaw will flood if the spark plug gets fouled or the ignition coil is faulty. Without adequate sparking power, the fuel entering the cylinder will not ignite. And after several pulls on the start cord, the cylinder will get flooded with gas.

  • A clogged air filter in a chainsaw may cause flooding by starving the carburetor of sufficient air to create the optimum air-to-fuel ratio, resulting in a too-rich fuel mixture entering the cylinder, effectively preventing the spark plug from firing.
carefully filling chainsaw with gasoline on a summer day
Having the right tools is essential when starting a flooded chainsaw. An ideal saw maintenance and repair kit should include a chainsaw cover, combination wrench, screwdrivers, and shop towels. And we recommend a file guide to help manage the chain. Extra sparkplugs are also a genius idea. They will come in handy if your flooded chainsaw fails to start after troubleshooting. (We also advise having a physical and digital copy of the chainsaw owner’s manual. It’s the single most vital component!)

How Do You Tell if a Two-Stroke Engine is Flooded?

The quickest way to confirm a flooded two-stroke chainsaw engine is to remove the spark plug and check if its electrodes are moist. If they are, then the cylinder is flooded. Here’s how to unflood a two-stroke chainsaw. Expel the fuel from the spark plug hole by pulling the starter cord 10 – 15 times with the engine switch OFF.

Will a Flooded Chainsaw Start?

A flooded chainsaw should start when excess fuel gets removed from the cylinder by pulling the starter cord several times with the choke off and the master control lever in the RUN position. Allowing the excess fuel in the cylinder to evaporate over several hours will help unflood the engine. 

What is the Proper Way to Start a Chainsaw?

Consult your chainsaw operator’s manual for the proper starting procedure. Generally, standard chainsaw starting procedures include:

  • Start by turning the engine switch ON.
  • Cold Start using the choke ON.
  • Warm Start using the Warm Start or Idle position on the master control lever (no choke).
  • Pulling the start cord till the engine is running.
  • Disengage the choke directly after the engine fires up and select the RUN position.  
using a chainsaw to clear tree litter and cut firewood
It’s easy to forget safety when researching how to start a flooded chainsaw! But that’s a critical mistake since over 36,000 people seek treatment at emergency departments from chain saw injuries each year. Chainsaw safety practices include regular chainsaw maintenance, using the saw from the proper position, and using hard hats, safety goggles, and ear plugs when cutting. (We also recommend a good pair of chainsaw chaps to help protect your legs from chainsaw kickback.)

Conclusion – After the Flood

There you have it, folks! A simple solution for a common chainsaw problem. You can actively unflood your chainsaw by removing the spark plug. Or you can let the beast stand for several hours to remove the flooding issue passively. Or, you can avoid the choke, select the Idle position, and buff up your biceps by pulling and pulling until that gnarly two-stroke rattle kicks in!

What about you? Do you have any tricks to help keep your chainsaw running well?

Or do you have more questions about how to unflood or start a flooded chainsaw?

Let us know in the comments!

Thanks again for reading.

And have a great day!

How to Start a Flooded Chainsaw? References, Guides, and Works Cited:

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