Husqvarna 455 Chainsaw - Lost Power ?

   / Husqvarna 455 Chainsaw - Lost Power ? #1  

MBTRAC

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Mar 28, 2012
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391
Location
NSW Australia
Tractor
Tractors16-600hp Farm & Earthmoving Equip, Trucks etc.
I'm trying to fix a Husky 455 that just about has us beat - the thing starts, runs & cuts fine for the first tank of fuel........but when hot from the second tank on just loses power & will not rev underload enough to get on the power band to cut with its usual power ( although it still starts fine & revs out unloaded).

We've tried everything we can think of - changed the air filter, cleaned the fuel pick up, wound the high jet up, checked the compression & compression release valve, changed the spark plug, cleaned the exhaust & the spark arrestor, checked out the choke is working ok, even swapped the carby with another of our 455's with still no result on the original saw.........first time we've ever experienced this issue with a Husky, & this particular 455 up until last weekend would cut all day "punching" well beyond its "weight" without ever an issue............appreciate your thoughts where to go next ? (& no it's not to a Stihl dealer ........:D)
 
   / Husqvarna 455 Chainsaw - Lost Power ?
  • Thread Starter
#3  
Could it be a problem with the ignition module?

Maybe, that's where I'm heading next......but other than lower than normal max revs there's no sign of missfiring or hard starting:confused:.......Thanks for your thoughts.
 
   / Husqvarna 455 Chainsaw - Lost Power ? #4  
well it sounds like you covered about everything I would have suggested.

So how about going to a Dolmar dealer instead:D

My only other thoughts are that it is possible it could be something OUTSIDE the motor/carb causing issues. Since it only happens once you run a tank through it (good and warm) and I assume it gets better once you let it sit awhile, could the bar, chain, or brake be warming up enough to cause some drag?? Perhaps nextime it does this, yank the B&C off real quick and leave the brake cover off and start the saw and see if it revs fine without any of that??
 
   / Husqvarna 455 Chainsaw - Lost Power ? #5  
Tank ventilation problems!?

We drilled a hole in the tank cap, that solved the problems when the saw was warm.
It's almost always a fuel issue with the chainsaw problems.
 
   / Husqvarna 455 Chainsaw - Lost Power ? #6  
Re: Tank ventilation problems!?

That was my thought, too. A malfunctioning/clogged fuel tank breather valve.

Here's a test:
As soon as you're finished running the saw when it's hot, crack open the fuel cap to let air in. You may hear a sucking sound as a result of air wanting to get into the tank to relieve a low pressure condition. This will prevent difficult restart if you are indeed having symptoms similar to "vapor lock."
 
   / Husqvarna 455 Chainsaw - Lost Power ? #8  
I had a 455 a few years ago with the same problem. After a short while it started up with the same issues on the first tank also. That is when my friend sudjested to replace the fuel takeup line and filter (they come as a single unit) and sure as his cat there was small almost unnoticeable cracks in the line.
 
   / Husqvarna 455 Chainsaw - Lost Power ?
  • Thread Starter
#9  
Thanks Guys I really appreciate your thoughts.

This 455 had me (& I might add our farm mechanics ) scratching our heads for ideas ( though if the truth be known our farm mechanics only gave it a cursory glance partly because they're busy, but more likely because they detest working on anything that does run preferably run diesel &/or have 4cyl's +)

In the end I took it to a Husky dealer & .........there was a tiny leak in the head gasket that only opened up enough to cause drama when hot - Thanks again for eveyone's input.
 
   / Husqvarna 455 Chainsaw - Lost Power ? #10  
.........there was a tiny leak in the head gasket that only opened up enough to cause drama when hot

-What is a "head gasket" on a 455 chainsaw?
 
 
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