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Service & Maintenance Question

    Gregory Davis
    Why is a 455 Rancher chain saw flooding after it is run and...escalated
    Service & Maintenance Question posted January 9, 2013 by Gregory Davis 
    5311 Views, 4 Comments
    Question:
    Why is a 455 Rancher chain saw flooding after it is run and then stopped?
    Details:

    I bought a new 455 Rancher chainsaw in Sep 2011. I was tired of problems with my Poulan Pro not starting. The saw was used for a max of 5 total hours. Took the saw out this past summer 2012 to use it again and it wouldn't start. Dealer cleaned out carburetor, black debris in carb screen was cleaned out. This fixed issue and it ran. Purchased non-ethanol fuel and dumped other ethanol mix fuel deciding to only use non-ethanol mix for saw. Ran saw with non-ethanol mix for about one hour total, dumped fuel out of tank and stored.

    Got saw back out late Dec 2012, used it for 10 minutes and then let it sit overnight, next day it won't start. Removed spark plug, totally wet, dried plug, pulled starter several times to dry out cylinder a little. Installed plug, saw started. Let set overnight, gas in compartment below carb, poured gas out and gas also came out of the carb throat.

    This saw is flooding when sitting still, totally unacceptable !

    Dried out again, started then stopped. Waited 2 minutes then stood saw up with carb down and saw tip in air, squeezed throttle to see gas running out of throat.

    Needless to say, I'm not  a happy consumer right now. I sprang for a higher cost and hopefully higher quality saw and honestly, I got years of trouble free operation from my much cheaper Poulan chain saw then the 455 rancher I have.

    I know what the dealer is going to say, warranty doesn't cover this.

    Any suggestions on what is causing this problem and how to fix it? I am a mechanic so I can change the carb gaskets but I'm not convinced that is going to help. I estimate there was at least 4-6 tablespoons of fuel in the carb compartment area and in the carb throat. This almost seems like some siphon effect going on.

    Any feedback appreciated.

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    Answer

     

    • Karla

      Gregory, First you did an excellent job of explaining your problem, and you are right it is a carburator problem. If the saw is still within the warranty period, I would recommend taking it to Husqvarna repair center. They should replace your carburator, tweak the idle and high speed adjustments and you would be on your way in 10 minutes.

      Here is what I think the problem is with the carburator, there is a metering needle valve inside the bottom of the carburetor, which controls the fuel into the carburator, when the saw is not running the needle valve should close and no more fuel should go into the engine. However, If the needle valve is stuck or a piece of debris is stuck on the end of the needle or in the valve seat then the valve can't close and the engine floods. If you decide to make the repairs yourself, you have three maybe four things to think about. (1) taking the carburator apart, you may be able to clean everything and use a can of propellant carb cleaner, and remove the needle and a really small spring inside the carburator cleaning the seat as well, but you may need a gasket/diaphram kit to put it back together, since sometimes the gaskets tear or get damaged. (2) You could go for the total carb rebuild kit which will include the gaskets/ diaphrams, and will include new valve needle, spring, and seat, this kit is very pricey. (3) you could go for a total new carburator which are very pricey but then you wouldn't have to rebuild. (4) you will have to have the knowledge to tuneup and adjust both the Idle  and high settings of the carburator properly. A good site to review is the "Walbro,com" site which has lots of carburator information that may help you, Also before you go ordering a carb repair kit, make sure you know which carburator is actually inside your chainsaw. Chainsaw manufacturers sometimes substitute different carburators. So remove the carburator from the chainsaw and carefully look at the Manuf. name (Walbro or Zama) and the numbers on the carburator castings which will identify the type and model number.

      I hope the above information helps.

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    • Gregory Davis

      Karl, thank you for responding so quickly !

      Note that my dealer already took the carb apart and cleaned out the black junk from the fuel screen, which allowed it to start. It has been flooding ever since.

      i took the carb apart this morning. I did find a little black debris in a hole on the diaphram side where the gas comes in. I took the needle and fuel lever out (not really a float :)) and it was clean, seat as well. I did notice that the diaphram that actuates the fuel lever is concave, ie, when assembled, the gasket pin will press on the fuel lever a little but I could not force any air, by blowing into the fuel inlet port after I got it re-assembled. If that gasket is concave such that it presses on the lever a little, is that normal?

      Maybe ethanol fuel has whacked out the gaskets enough, especially the one that presses on the fuel lever float thing, to pre-load the fuel lever too much. I have been doing mechanic repair for 30 years so bring on the mechanics :)

      I also did find this carb on the Walbro site and have the technical description and parts breakout. The idle screw, low and high screws are adjusted. Used it today and every time we need to start it, we have to hold the throttle open some to get it to start, this is with no choke and no priming. So it's still flooding some.

      Husqvarna only covers carburetors for  a year, which sucks really ! I've already checked into this. So I'm going to try a new gasket set and see what happens. Now that I'm not using ethanol fuel anymore, maybe it will last longer before acting up.

      I must admit that I'm dismayed about Husqvarna so far. I had a Poulan Pro for over 10 years and it started every time without effort, less then $200 cost. This 455 is at least twice the price.

      I hope I get it fixed with the gasket set. I'm going to buy a gauge to check the fuel lever setting also.

      If you know that Husqvarna should repair this saw for free I'd like to hear more about that too :)

      thanks again Karl !

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    • Karla

      Gregory, The fuel metering lever is still set to high if your still flooding the engine. You will need to open up the carburator again and bend the metering tab down just a 1/16 " or so. You do not need to remove the needle valve and spring, but hold down with a small screwdriver the lever part at the needle end and push down on the opposing end of the lever with another small screw driver, just a very small amount, too much bend and the fuel will shut off completely. Also after making an adjustment press down on the opposing end and insure the lever still lifts the needle valve. Put it back together and try again, it may take a couple of tries to get it right. It appears to be a crude adjustment but this is the only adjustment that controls the flow of fuel from the tank into the carburetor and into the engine, and is more like an on/off contol. It is the same as a float in a carburator, except by being a spring loaded needle it will allow the engine to run no matter what position you hold the carburator in or position of the saw.

      Oh, I also wouldn't bother buying a gauge, I have a gauge but always set it by trial and error and experience.

      A new diaphram kit will probably help too, I always replace the diaphrams they have to be very flexible, since it moves that metering needle in very small increments.

      Also a good test that you have the carburetor metering set correctly, after its idling and running correctly. Is to start the saw and hold it in different planes, left, right, upright, and vertical the saw should continue to run in any position that you put the saw into.

      I hope the above information helps.

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    • Karla

      Additional information, unlike the float in a bowl on a standard lawnmower which shuts the fuel off, the needle valve arrangement, lever, spring and metering diaphram  work together to allow the chainsaw to be put in any position and run, and when the saw is shut down to shut the fuel off. If you have a badly deformed metering diaphram then it will need to be replaced, and probably no adjustment to the metering lever will compensate for it. However, I have adjusted some really bad looking metering diaphrams and compensated for their bellow by adjusting the lever and they still work.

      Anyhow, Please let me know If you have it working, you asked for the mechanics of how it works, the Walbro write up and description does a far better job then I could do. Just remember when the fuel fills up in the carburator the metering diaphram pushes down from the weight of the fuel, allowing the spring and level to close the needle valve, as the fuel is consumed inside the carburator the diaphram moves up opposing the force of the spring and allowing the lever to open the needle valve again filling the carburator.

      I hope this helps.

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