You've given great info. I am about to take mine to my mechanic to have him inspect the brake lines and these areas. Should it need replacement, I was curious if you could point me in the direction you went to locate these parts. I am suspicious of this being the culprit, since I still smell vague fumes coming from around the rear quarter panel around the rear passenger door up to near the gas filler door, but I already got a new Stant cap, so I know the cap and seal is good. Thanks!

 

My 2011 came with a new Stant cap, it had failed after just three weeks, replaced with correct fuel cap from AC Delco.
the fuel lines I suspected when I bought it last August and confirmed the leak by looking up just in front of the drivers side rear tire, were the insulation tube ends , it was wet with fuel but not dripping on the driveway.

https://www.chevyhhr.net/forums/how-...follies-62310/

for the EVAP canister vent and purge valves they were both only three weeks old , I replaced them because of codes indicating they had failed, I ordered the AC Delco parts , specific to my year and engine from RockAuto, don’t forget the discount code.
It was very apparent to me the PO wasn’t informed or didn’t care to install anything but cheap parts in order to sell the car .

 

put a vacuum cap on the nipple, leave it plugged in, vent the line to the wheel well and turn the code off via hpt. I did this to my built ss 6 years ago and there have been no issues. The evap system is useless