If your TT Z is like mine, the fuel check-valve/roll over valve is old and clogged, and cleaning it didn't fix the problem. The part number for it is 17370-30P00, but it's discontinued. After much searching, I found out there is an identical Nissan replacement under a different part number: 17370-89900. I haven't run it yet, but I plan to, and I'm hoping this will also solve the issue of pressure escaping from the gas cap every time I have to refill. I'll report back with results, but see the photos for the comparison between the two parts. Sharing in the hopes of giving back to the community.