it was kind of strange, I took fuel cap off, it would suck, but it wasn't venting even with cap off(not fully). it would suck some, but I felt I still had vent issues cause the water separator wouldn't drain properly. and it still works, like too well, every couple of tanks I need to drain some. at least with separator not draining properly. so next tank full I threw in a can of lubromoly. problem seems to be clearing up. pressing vent now re-allows me to get in 1-1.5 gal more, and separator drains some on its own. maybe I ll open drain for a few minutes to get more thru. I inspected cap and looked clean, im going to get a new oring for cap.
I really don't want to have to go in and clear out expansion tank and lines, but I was thinking of taking hose off vent and that gravity thing, and blowing air thru both(catching on other side), and replacing hose.