Originally Posted by
DBGrif91
If this is just FUEL VAPOR, what exactly is the point of having the canister? Why couldn't the vent line run direct from the tank to the TB? And, further more, if this were the case, why would a purge valve solenoid be necessary? Why couldn't the canister and the purge valve be eliminated altogether and just have a line running straight from the tank to the TB?
The function of the canister is to store vapor to be used by the engine at a later time. The function of the purge solenoid is to allow the engine to use the vapor when told too by the computer. They cannot be bypassed in the manner you speak because engine vacuum would create negative pressure in the tank, and suck raw fuel into the engine.