Husqvarna 236 Vent Problem

[aditzuuu]

Hello guys. I have a problem with a Husqvarna 236 chainsaw.
One day i wanted to fill up the fuel reservoir and surprise...all the fuel was leaking out. After investigation, i've discovered that all the fuel it's leaking through the air vent of the fuel reservoir. The Check Valve(Duckbill) and the Plug were pushed out. The Plug i didn't even found it again. I inserted the Check Valve again into the vent hole, but when i accelerated the chainsaw was pushed out again.
It looks like that it's some kind of pressure building up in the fuel tank(positive pressure). What are your thoughts about this? I will have to order another Plug. But i don't know. That plug it's like some air filter. It will help the Check Valve to remain fixed in the hole?
So, to be clear. The pressure in the fuel reservoir gets higher when i accelerate the chainsaw. In that moment the duckbill it's being thrown out.
It's funny. The air vent helps you to avoid negative pressure in the fuel tank. But, I actually have problems with the positive pressure. What its creating this pressure in the fuel tank?

 

[pioneerguy600]

Fuel expansion, happens if one agitates fuel even in container, shake the fuel and the container will well up.

 

[aditzuuu]

I understand that the fuel/ fuel vapours can appear and increase the fuel pressure.For example if you let the chainsaw in the sun, if the engine heats up very much etc. But your answer doesn't solve nothing. I have the chainsaw for 4 years and the problem didnt appear until now

 

[pioneerguy600]

I understand that the fuel/ fuel vapours can appear and increase the fuel pressure.For example if you let the chainsaw in the sun, if the engine heats up very much etc. But your answer doesn't solve nothing. I have the chainsaw for 4 years and the problem didnt appear until now

You asked what is causing the this pressure in the fuel tank, it is caused by the fue being agitated from the vibration of the engine running, the fuel expands and causes this pressure..

 

[aditzuuu]

You asked what is causing the this pressure in the fuel tank, it is caused by the fue being agitated from the vibration of the engine running, the fuel expands and causes this pressure..

But why the check vv is being thrown out?

 

[pioneerguy600]

But why the check vv is being thrown out?

For you to determine, can`t fix it from here. Was there any type of retainer holding the check valve in?

 

[aditzuuu]

There was no retainer. You just push the check valve in a the vent hole

 

[pioneerguy600]

Does the sintered bronze disc fit in tightly after the duck bill check valve? it appears that it is only a friction fit from that disc that would hold the check valve and itself in the bore.

 

[aditzuuu]

I don't know about that sintered bronze disc. That disc was also pushed out and lost. When i'll receive a new spare for it i will check. But i am thinking to use some loctite only to be sure.