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Service & Maintenance Question

    ray nixon
    I own a 455 Husqvarna. The saw boggs down as soon as you put...escalated
    Service & Maintenance Question posted February 17, 2014 by ray nixon 
    12294 Views, 4 Comments
    Question:
    I own a 455 Husqvarna. The saw boggs down as soon as you put pressure on the chain or just power up the saw. Do I need to adjust the high speed jet. If so, do I need a special tool ?
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    • Karla

      Ray,

      The problem could be a number of different things, so I will list a few things that you will need to check. You also did not say  what year or how old is the chainsaw ? Age matters with respect to the internal carburetor parts which have diaphrams that get brittle over time, so I will list some of those items in case the chain saw is a few years old.

      First, start with a clean or new fuel filter, many times the fuel filter when it gets varnished over or starts to get plugged, will still allow enough fuel thru the filter to allow it to start but when you put it under load, and needs alot of fuel at  wide open throttle (WOT), then the engine bogs down, so check or simply replace the filter first. I didn't mention the fuel, but also make sure your using a fresh mix of fuel and engine oil too.

      Next, check that the air filter is clean or new. A dirty air filter may allow enough air through it to start  the chainsaw, but when under load and at WOT, will not allow sufficient air to keep it running, and hence it bogs down.

      Next, Make sure your primer bulb is working properly, not only does the primer bulb initially get fuel into and through the carburetor but it also has a small check valve inside the primer bulb to maintain a full line of fuel into the carburetor. I have seen the check valves go bad, and you can still start the saw but it will not run at WOT. To test the primer bulb press it several times and watch the fuel lines or primer bulb to make sure fuel is moving through it, then let it sit for a while, and see if the primer bulb drains down or goes empty. If it does, then its a bad primer bulb check valve.

      Next, especially if its a few years old, and has been well used, remove the muffler and inspect/ clean the muffler, spark arrestor inside the muffler, and cylinder exhaust port. I have seen many of these engines that build up carbon, especially on the spark arrestor screen, and once the carbon blocks most of the exhaust, the engine cannot pull in fresh air and fuel, and again the engine will give the same symptoms under load where it bogs down. It also may be more difficult to start when it has a clogged exhaust.

      Next, the carburetor - My pattern of troubleshooting is usually leave the carburetor till last, and check out everything else. Sometimes making an adjustment will fix the problem or sometimes it will compensate  for something that is going wrong, so be careful with making adjustments, and ask yourself why? It ran good before, what has changed and now I need to make adjustments ? A number of things to check, again especially if its a few year old chainsaw, on the carburetor. If I suspect the carburetor is the problem, I usually save alot of time by just simply taking it apart, cleaning it thoroughly both low, and high jets with a can of spray carb. cleaner, and also the fuel inlet screen inside the carburetor, then putting a new metering and fuel pump diaphram, and gaskets in the carburetor (basic diaphram & gasket kit ~ $5.00), checking the various carburetor internal adjustments, and putting it back together. Its fairly easy after you have done a few.

      Finally, after the carburetor is clean, and everything is like new, a slight tweak of the adjustments for both low, "L" and high "H' may be required, but they are usually within the limiters range which were factory set. But I definitely recommend taking the time to check everything else out before you try to fix the carburetor. If your Not familiar with carburetors you also, may just want to take it to an Authorized Repair Center, where they can do the cleaning and adjustments for you.

      I hope this helps, Please give me a shout if I can be of any further help. I don't know if I asked how does the engine appear to start? Does it start on one or two pulls with no problem every time ? If Not the bogging down could be due to an internal engine problem, but you would also Know this by how it starts. So If it starts OK your probably Not an internal engine problem, But bogging down under load could be another symptom.

      PS. I am Not a Husqvarna Representative or Authorized Repair, Just an experimental chainsaw person.

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      • Amy Steuer

        Thank you!! I am printing your easy to read and easy to follow steps to troubleshoot the Husqvarna 455 chainsaw!! Since your advice probably applies to most any chainsaw that is bogging down after it starts, I am going to make multiple copies of your advice and post them in key places for our landscape employees to read and check off the very next time they have that common problem with our variety of chainsaws!  Again, thank you for your helpful reply!

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    • Karla

      Ray,

      I forgot to answer your question about a special carburetor tool, It depends on the carburetor that was installed in your Model 455 chainsaw. Husqvarna puts different Manufacturer of carburetors in the same model, typically they are "Walbro" or "Zama" Manufacturers, the Walbro ones are usually a small screwdriver slot but there may be plastic limiter caps over the adjusting screws, which will only allow you to make minor adjustments or maybe 1/4 - 1/2 turn.

      I don't know which carburetor you have inside your chainsaw, you may be able to see a name on the carburetor if you remove the air filter and carefully look at the carburetor, also if you can see letters and numbers on the carburetor, and they start with the letter "C", then its probably a Zama. and if the letters and numbers start with a "W", like a "WTA" or WTEA" then its probably a Walbro.

      I hope this also helps, and sorry to be so wordy!

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      • Amy Steuer

        Again, thank you for your informative and easy to follow advice about whether or not the chainsaw needs a special tool to troubleshoot and adjust the carburetor!  I am printing several copies of this advice too, and will make sure everybody who has the privilege of using our chainsaws reads your two replies at least twice a year!

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