Evap/Emissions System Question

[infernosg]

I've come to the conclusion I can't properly connect the charcoal canister and oil catch can to a vacuum source without a purge control value. Connecting them straight to the intake manifold applies the most vacuum at idle, which isn't ideal. So for now the catch can and the canister will be vented to the atmosphere. The only question l have left is if the canister serves any value if it's vented or of it's no different from having no canister at all.

[RETed]

The primary function of the charcoal canister is to contain the fumes from the gas tank.
Due to current, modern (fuel system) emissions rules / laws, even vapors from the fuel tank are not supposed to escape into the atmosphere...including under conditions such as filling gas into the gas tank.
Ideally, when you fill gas, the incoming gasoline displaces air space / vapor in the gas tank...
Where does that all go when you fill the gas tank?
It's supposed to be captured by the charcoal canister and associated emissions components.

The secondary function is also to let the air space / vapor displace without backing out and up the filler neck.
Most gasoline pumps have a back-pressure safety shut-off that stops the pump when it senses too much back-pressure - i.e. when the gas tank gets full.
If you didn't have this charcoal canister system to handle the displacement, it would make it a tough time trying to fill your gas tank from most gasoline pumps nowadays...

Venting is to atmosphere works perfectly fine...
Like I said before, if you have no worries about emissions, then just vent it.


-Ted