Husky 455 Fuel Tank Pressurizing

Arborist Forum

Help Support Arborist Forum:

Two-Smoke

ArboristSite Lurker
Joined
Dec 29, 2021
Messages
5
Reaction score
4
Location
St. Landry Parish, Louisiana
Recently inherited an 08 Husqvarna 455 from my father in law. He had been fairly rough on it cutting allot of firewood and neglecting maintenance in several areas. The saw had sat with gas in it for the last 3 years or so. When I got the saw it started up but after 5 minutes of running it the motor started to run erratically. From there I decided to clean it up and get it back to “reliable condition”. First I took the air compressor to it and blew out the years of sawdust caked in every imaginable location, replaced spark plug, replaced fuel filter, replaced air filter, rebuilt carburetor (diaphragms, gaskets, cleaned screen, cleaned ports), replaced primer bulb, replaced fuel line from carb to bulb, replaced fuel line from bulb back to tank, replaced tank vent. Started the saw, got carb tuned using inductive tacometer, and test ran saw. It runs great until the motor gets good and hot causing the fuel tank to pressurize resulting in the saw stalling while idling. I thought replacing the tank vent would cure this issue but it has not. The only thing on my radar which I have not replaced is the fuel line going from the fuel filter up into the bottom of the carb. I just took it off a few hours ago and inspected it finding no holes, tears, or leaks. Any help would be much appreciated. Thanks in advance.
 

SteveSr

Addicted to ArboristSite
Joined
Mar 3, 2003
Messages
2,609
Reaction score
1,875
Location
Raleigh, NC
Tank vents in modern saw are designed to let air into the tank to make up for fuel being used but not to let gas fumes (EPA) out. It is normal for them to build some pressure.

You have another problem like an air leak that happens when the motor/manifold gets hot. You may also still have a carb issue. Did you check/set the metering lever height?
 

Old2stroke

Never too many toys
AS Supporting Member
Joined
Jan 24, 2016
Messages
1,244
Reaction score
1,705
Location
Ottawa, Canada
When it stalls at idle, you have to know if it's due to a lean or rich condition. When it's idling and the rpm starts to drop, back the L screw out a bit and see if it helps, if it does, you have a lean condition that could be caused by seal air leak or leaking nozzle check valve or a few other things. If you turn the L screw in and the rpm picks back up, then you have a rich condition which could be caused by the tank pressure building up and exceeding the pop-off pressure of the carb, you can easily test this condition by just loosening the fuel tank cap to relieve tank pressure.
 

Two-Smoke

ArboristSite Lurker
Joined
Dec 29, 2021
Messages
5
Reaction score
4
Location
St. Landry Parish, Louisiana
When I run the saw without the cover on and look at the two fuel lines going into the fuel tank I can see fuel slowly oozing out as i rev the engine. I test ran the saw last week and put it away to go visit family. When I came back i could see where fuel had been oozing out of the tank vent and up through the grommets at the two fuel lines that go into the tank. All this was happening without the saw running.

The saw idles perfectly until I make two or three big cuts (30 seconds or more) and then it starts to stumble.

Can you further describe what this insta-die reaction looks like Backstage? Thanks again for your feedback.
 

SteveSr

Addicted to ArboristSite
Joined
Mar 3, 2003
Messages
2,609
Reaction score
1,875
Location
Raleigh, NC
When I run the saw without the cover on and look at the two fuel lines going into the fuel tank I can see fuel slowly oozing out as i rev the engine. I test ran the saw last week and put it away to go visit family. When I came back i could see where fuel had been oozing out of the tank vent and up through the grommets at the two fuel lines that go into the tank. All this was happening without the saw running.

The saw idles perfectly until I make two or three big cuts (30 seconds or more) and then it starts to stumble.

Can you further describe what this insta-die reaction looks like Backstage? Thanks again for your feedback.
Also would be good to verify your fuel line and purge bulb plumbing. You should be able to push on the purge bulb forever and notice fuel filling from the tank and then being pushed back to the fuel tank. You won't be the first one to muck up the plumbing on one of these.
 

Backstage

ArboristSite Operative
Joined
Oct 23, 2021
Messages
219
Reaction score
277
Location
Trying to find my tape measure
It’s pretty self explanatory. To see it in action as an experimental control, spray a bit in through the air filter. Saw shuts off almost instantly. Pull the cord a couple times and it’s back up.
 

ctcowboy

ArboristSite Lurker
Joined
Jan 6, 2022
Messages
7
Reaction score
5
Location
ct
When I run the saw without the cover on and look at the two fuel lines going into the fuel tank I can see fuel slowly oozing out as i rev the engine. I test ran the saw last week and put it away to go visit family. When I came back i could see where fuel had been oozing out of the tank vent and up through the grommets at the two fuel lines that go into the tank. All this was happening without the saw running.

The saw idles perfectly until I make two or three big cuts (30 seconds or more) and then it starts to stumble.

Can you further describe what this insta-die reaction looks like Backstage? Thanks again for your feedback.
I have a similar issue-- did you end up figuring out yours? With mine I also hear a sucking sound presumably coming from the return grommet...this sound occurs when i turn the engine over or push the purge valve (which incidentally only fills up half way ). I have replaced all fuel lines and the purge valve with 2 separate ones.. i took before pics and have a twin saw to compare with so its hooked up correctly...
 

Two-Smoke

ArboristSite Lurker
Joined
Dec 29, 2021
Messages
5
Reaction score
4
Location
St. Landry Parish, Louisiana
I have a similar issue-- did you end up figuring out yours? With mine I also hear a sucking sound presumably coming from the return grommet...this sound occurs when i turn the engine over or push the purge valve (which incidentally only fills up half way ). I have replaced all fuel lines and the purge valve with 2 separate ones.. i took before pics and have a twin saw to compare with so its hooked up correctly...
Not yet. Waiting on the two grommets to come in and if that doesn't work I'll probably try a new carburetor. There are 3 fuel lines total. Don't forget the one coming from the tank up into the bottom of the carburetor. I'll keep you posted. Good luck.
 

ctcowboy

ArboristSite Lurker
Joined
Jan 6, 2022
Messages
7
Reaction score
5
Location
ct
The am carb kit I bought came with replacement fuel lines as well so yes that's been replaced. I was having bogging in upper revvs.. if I were you I'd replace the fuel line you're speaking of while you're doing the grommets bc it will buy you some time in the future.. my return line was bad right at the point of entry which couldnt be easily seen on visual inspection..(still wasn't my main problem but one of them)...Ive got a new tank vent on my bench so that's where I'm headed next...
 

ctcowboy

ArboristSite Lurker
Joined
Jan 6, 2022
Messages
7
Reaction score
5
Location
ct
Fyi... Tank vent (and bad fuel line) was my issue... then new carb compounded the issue... If you get an AM carb from Amazon.. mine was not adjusted correctly from the factory...(knock off limiting tabs B4 installing) Metering valve height was wrong and the saw loads up and stalls with bar tip up ...had to lean it out to 1 turn out on L to get any throttle response...level it screams again. Gonna be forced to rebuild stock carb once I get some use out of it...
 

Old2stroke

Never too many toys
AS Supporting Member
Joined
Jan 24, 2016
Messages
1,244
Reaction score
1,705
Location
Ottawa, Canada
Fyi... Tank vent (and bad fuel line) was my issue... then new carb compounded the issue... If you get an AM carb from Amazon.. mine was not adjusted correctly from the factory...(knock off limiting tabs B4 installing) Metering valve height was wrong and the saw loads up and stalls with bar tip up ...had to lean it out to 1 turn out on L to get any throttle response...level it screams again. Gonna be forced to rebuild stock carb once I get some use out of it...
Don't be surprised, AM carbs are NEVER factory adjusted for your saw to run right, although the control lever height is often right.
 

Two-Smoke

ArboristSite Lurker
Joined
Dec 29, 2021
Messages
5
Reaction score
4
Location
St. Landry Parish, Louisiana
Fyi... Tank vent (and bad fuel line) was my issue... then new carb compounded the issue... If you get an AM carb from Amazon.. mine was not adjusted correctly from the factory...(knock off limiting tabs B4 installing) Metering valve height was wrong and the saw loads up and stalls with bar tip up ...had to lean it out to 1 turn out on L to get any throttle response...level it screams again. Gonna be forced to rebuild stock carb once I get some use out of it...
 

Alanmurphy6912

ArboristSite Operative
Joined
Dec 7, 2020
Messages
113
Reaction score
60
Location
Freedom
Recently inherited an 08 Husqvarna 455 from my father in law. He had been fairly rough on it cutting allot of firewood and neglecting maintenance in several areas. The saw had sat with gas in it for the last 3 years or so. When I got the saw it started up but after 5 minutes of running it the motor started to run erratically. From there I decided to clean it up and get it back to “reliable condition”. First I took the air compressor to it and blew out the years of sawdust caked in every imaginable location, replaced spark plug, replaced fuel filter, replaced air filter, rebuilt carburetor (diaphragms, gaskets, cleaned screen, cleaned ports), replaced primer bulb, replaced fuel line from carb to bulb, replaced fuel line from bulb back to tank, replaced tank vent. Started the saw, got carb tuned using inductive tacometer, and test ran saw. It runs great until the motor gets good and hot causing the fuel tank to pressurize resulting in the saw stalling while idling. I thought replacing the tank vent would cure this issue but it has not. The only thing on my radar which I have not replaced is the fuel line going from the fuel filter up into the bottom of the carb. I just took it off a few hours ago and inspected it finding no holes, tears, or leaks. Any help would be much appreciated. Thanks in advance.
Are yo sure your not confusing the vent tank vent with the return line for the primer? If I remember correctly the tank vent is actually under the recoil cover housing and is a white plastic nipple looking vent that is recessed in a hole. Not trying to sound dump or make anyone else look dumb just thought I'd ask. I too had a 455 rancher and it ran erratically and I replaced carb and all lines vent etc. And it still acted funny. I ended up selling it and now have a 460 rancher that I rarely use
 

Latest posts

Top