The vapor canister is tied into the intake system already via the purge valve, a solenoid controled by the PCM. Under some conditions (basically warm engine at cruise) purge valve opens (it is really PWM'd) and sucks stored vapors into engine. PCM knows when purge valve is open (obviously) and adjusts other parameters accordingly. Disabling any part of the EVAP system will end up turning on the CEL and setting one or more DTCs.
how can i test to see if the solenoid if opening? and do you know where the vacuum hose is supposed to connect because i have it connected to a metal "T" that is on the metal line that connects to the PCV valve. i have no idea if this is correct.
Leaking injector O rings? Injector leaking externally? Leaking fuel line disconnects? If it smells of gas when driving at highway speeds I would suspect fuel leakage under the hood going into the cabin air intake. It doesnt take much of a leak to smell really bad. If the cannister or EVAP system was leaking, the EVAP system would fail the self test and the CEL would be on.