Okay so im at my witts end with this problem. Got a 2005 grand prix gtp. Code p0446. I have replaced the purge solenoid, vent valve, filler neck, fuel pump, and vapor canister. I just took it to get a leak test done, leak found and sealed. STILL NO VENTING. We bypassed the vent valve, still no venting. I dont know where to look next.