Clearing a Flooded Saw

This is one of those topics that usually generates many different opinions due to personal experiences. Anyone that has been around small engines, or enjoys working on 2-stroke motors will usually be somewhere along the lines of what we are going to suggest. With that said if you have different ideas or another way that is tried and true for you, then you are welcome to throw it in here for everyone to discuss.

Troubleshooting a flooded saw in the field could make or break whatever task you have been assigned to. We all know that if the saws are not checked, ran and maintained it becomes very easy for them to flood from the constant bumping around that happens while driving around town.  If they have started to flood you will notice the blue smoke that burns off in the first 5 seconds or so of getting them fired up. There are many different scenarios of when and how the saw may flood. One very common way is operator error. This can happen when someone initially attempts to start the saw but goes through the wrong procedures.

Every saw starts with just a little different touch. One of the best ways to know each of your saws is when you start them in the mornings. You begin to pick up on the little differences of each one. Some may need choked longer, some may need a quick half choke, others may be a one pull start if your quick on the choke. Either way we should know what is normal and what is not.

For the sake of this scenario we will say that the saw was flooded by starting it wrong. So the saw is cold and we have cycled it enough times with no spark that it is successfully flooded. What’s next?  This is where our troubleshooting method comes in, we must have an aggressive way to clear the saw in a timely manner or else it is out of service. We know time will correct floods eventually but that is what we don’t have. We have all heard pull the plug out and let it air, which is fine if we are at the station and not in need of a working saw. 

Here is a quick tried and true way that works with a great success rate when you need to clear a flooded saw immediately. A solid understanding on how the choke and fuel system works will only increase your success rate with this tactic.

1st- we recognized the problem (flooding) and we switch to our troubleshooting start. 

2nd-We place the ignition, if present in the on position enabling a spark. (This will be one of the points that I am sure will be debated…but hang with us)

3rd- Next we want the choke open/off, this allows the maximum amount of air to flow through the carburetor, which is key to clearing out the saw.

4th- You will squeeze and hold the throttle which causes our saw to be “wide open”. This is the second step in having the maximum amount of air with the least amount of fuel coming through the saw. Don’t be concerned that your dumping fuel in while the throttle is open, because your not. The saw will not effectively start pulling the full fuel mixture until the engine is running full speed. This is why we get maximum air without max fuel.

5th- With the choke and throttle wide open you want to grab on to the pull cord and cycle the saw quickly about 8 times. Typically this will effectively clear the saw enough that we can focus on starting it. This brings us to the reason of why we like to leave the ignition on. Many times you may get a “hiccup” out of the saw and be able to get it running quickly after you cycle it. If not we move to our next step.

Now that the saw is cleared you will move into starting operations as close to normal as possible. These steps can vary slightly based on what you hear and feel with the saw. Put the choke back to the on/closed position and give it a few pulls, maybe move into a half choke based on what you hear, and then most of the time you will have your saw started. Make sure you are practiced and comfortable with these steps so it becomes routine when you have to do it on a real scene. That rare instance will always exist where the saw is just not going to start that day for many unknown reasons. However this  technique, if done properly will get your flooded saw running again almost every time.

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16 Comments on “Clearing a Flooded Saw”


  1. There are a few other tricks that may just make it a bit easier when doing this procedure. They were not added into the article in order to keep it simple but we welcome those who had some input on “style points” (chain brake, decomp, ect) for an even smoother startup.

  2. Robby O Says:

    Great stuff….I will definetly give it a chance and share it with my crew.

  3. TRUCK 4 Says:

    Well as mentioned, there are a few extra steps that may also contribute to a more smooth start up operation. The first part to starting a saw, and more importantly a flooded saw, is to depress the decompression button on your saw. This button will add to the air flow by keeping the cyclinder slightly open during compression strokes of the piston. Once it sputters though, it will close and you will need to depress it again if the saw did not start. Also, if the saw still continues to to not start, try also releasing the chain brake. This will free up the centrifugal clutch housing during the startup of the saw allowing free motion of the working parts. Take caution, however, because this means that the chain will will now move freely and because it is in the startup phase it will rev up to full throttle and could cause serious injury! Be very careful!


    • Well said, thanks for adding those tips. It brings up another good point of knowing your saws and remembering where your decompression switch is and when to use it. Based on the size and type of your powerhead you may not even have one! Thanks for helping put this article together.

  4. Ryan Says:

    This isn’t sexy stuff, just good practical information. Good job brother. keep it coming.

    Thanks,
    -Ryan G

  5. GaryLane Says:

    Good little write up! Thanks for the refresher!

  6. L Chapel Says:

    When starting a cold 2-stroke engine, run it a half throttle to bring the engine temperature up before giving it the beans. This will help prevent piston slap and extreme engine wear. Also, never let a chain run while it’s sitting on a hard surface. The clutch and engine internals will thank you for it.

    • TRUCK 4 Says:

      Excellent point Lt. The point about not running the chain on a hard surface. I try to let all of the saws warm up in the grass, if you fire house has grass, or like you said, holding them which will minimize the vibration to the internal components.

    • Chris j Says:

      We have been instructed by huskavana and stihl not to run then half throttle to warm up during our daily tests but rather to run them full throttle. This was not by sales reps but by engineers. We tried to verify it and they assured us its a 2 cycle, not 4 And the engines are designed to run wide open. Maybe it’s my 4 cycle mind, but I was shocked to here that.


      • Chris, I prefer full throttle also…but that is after I let it warm up idling for a bit first. I think the roughest start is from firing it up and instantly running a wide open throttle.


  7. Couple of things about the decompression button. If you are not strong enough to start a saw without decompressing the button that you should not be allowed to ride in the back of a fire truck, that being said you should decompress the button every time you want to start your saw. The biggest reasons that you should decompress the valve is that it is very hard on your recoil, in saws that get routinely get started without the use of the decompression valve they will have “slaking” in the pull cord and will have problems recoiling the pull cord. The other reason that the decompression valve should be used is that when the saw is started the engine compression is pushed towards the decompression valve, if there is no were for that compression to go than it will slowly were the gasket inside the decompression valve down. When the valve gets worn down it will cause the valve to leak, this leak will cause compression issues in your saw and you will have a very had time getting full rpm out of your saw.

    Just my .03 (price has been adjusted from Canadian to USA funds)!!

    Stay Safe Brothers
    Andrew Brassard
    Brotherhood Instructors LLC


  8. […] This is one of those topics that usually generates many different opinions due to personal experien… […]

  9. C Piepenburg Says:

    Great write-up! We just went over this the other day with some guys at the firehouse. Worked like a champ!

  10. M. Cason Says:

    Key is knowing your equipment. One of my trucks has a K12 that is very hard to start with the decompression button, but will start with first or second pull if you leave it alone. You just have to have the strength for the job. Know your tools and yourself and life will be good.

  11. FF Khan Says:

    When should you have the choke fully opened, half choked or fully closed? What do you listen/look for?


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