Echo CS301 - How in the world do I get to the fuel tank vent?

[Chachi8179]

I'm new to the forum, and chainsaws in general. Trying to tune up an Echo CS301 that was given to me recently, but hit a road block. With all the covers off, I still can't get to the fuel tank vent. The little guy runs for a while, then does when I let off the throttle. There's also a sucking sound when I open the fuel tank, like it's under a vacuum, so I think I'm on the right track.
Any help would be greatly appreciated.
Thanks, guys.

 

[Wood Doctor]

And, the the holder:

Not much to either one. A couple of little guys.

 

[StihlSolo]

The Echo CS-301 is like the 280E: it has a still air box for the carb. Take of the front cover and air filter, the tank vent is at the end of a hose in the still air box. See attached.
Don't try to solve vacuum problem by leaving the tank vent check valve off. With the check valve gone, gas tank fumes and liquid could get into the still air box.
Do make sure the air filter is not blocked up or the carb starts drawing air from wherever it can, like trying from the gas tank through the tank vent check valve, which then closes.

 

[Chachi8179]

The Echo CS-301 is like the 280E: it has a still air box for the carb. Take of the front cover and air filter, the tank vent is at the end of a hose in the still air box. See attached.
Don't try to solve vacuum problem by leaving the tank vent check valve off. With the check valve gone, gas tank fumes and liquid could get into the still air box.
Do make sure the air filter is not blocked up or the carb starts drawing air from wherever it can, like trying from the gas tank through the tank vent check valve, which then closes.
View attachment 948693View attachment 948694

I traced that line back under the top handle, but still don't see where it comes out. Another post says to remove the flywheel...