Brian.. If you haven't replaced the purge canister behind drivers rear wheel, it's worth shot gunning a $15 part on. It's the most common. It's also open and will leak smoke when you test unless the system is commanding it closed.
Here's the one I built.
How to Make a DIY Smoke Machine - YouTube I had a small regulator laying around and set it low. Worked well. As I was replacing canister, I connected the smoker to it's hose going into the tank with the gas cap in and the tank expanded with no smoke escaping. This led to be believe it was only the canister. 4 days and all good so far.