vapor can bypass (rebuild/replaxce) question ('84 FI)

[essenz]

So I've gotten differing responses on facebook, and frankly I dont fully understand the relationship between vacuum and the vapor line. This is on an 84 fuel injected 2L.

The stock setup runs a vacuum hose to the charcoal canister. The canister is open to the air via the top cap, so that means the intake plenum pulls in a baseline amount of air - which I assume you compensate for when setting the idle.

My canister is leaking charcoal out of the bottom into the vapor line, it was actually clogged, and a whole mess. I've seen info only on how to replace the insides, but in the mean time I want to drive.

I've been told to just connect the vacuum line from the intake plenum directly to the vapor line running to the tank, bypassing the canister. But.... This doesn't make sense to me, the gas circuit now has no way to vent or release pressure? Also, when I try to do this, my RPM increases and I cant get it down below 1000rpm in neutral. If I poke a few small holes in this bypass line, RPM drops a bit.

I'd really like to understand this better.