McCulloch 1-71 fual cap vent help

[Gottoolz]

Does anyone have a parts diagram of how these seals go in the venting system of this 1-71 fuel cap?
When I take cap off, it releases pressure built up in tank as a result of it not venting.
I took it apart and not sure how it goes together.
Thanks

 

[heimannm]

It is supposed to hold pressure, and prevents a vacuum as the fuel is consumed.

I looked through my electronic IPL's and don't find any that show that cap arrangement. I'll try to remember and look at some hard copies and see if I can find one there.

Mark

 

[Gottoolz]

It seems fuel leaks from carb when the saw it sitting. I thought it was from pressure building in tank.
Maybe its from something else

 

[heimannm]

The carburetor should hold 10 PSI without leaking. Most of the time the tanks also have a "pop off" that should relieve any pressure in excess of what the carburetor will tolerate.

Mark