So it looks like newer Honda's 2011 and 2017 are vacuum systems? Since there is no pump to pressurize it. I find it funny that all the video's that claim to show how the gas cap works, never show a thing about it. Since a smoke test supply's positive pressure and a gas cap is not supposed to leak during such,
I guess, the valve in the gas cap blocks pressure from escaping, and would allow air into the tank?
Then the question of tank pressure, there is pretty much zero information on that, you can't accurately test a pressure switch not knowing that information. It is claimed the standard evap smoke machine pressure is 1 psi, anything over that can cause damage?
I can see where evaporation and heated returned fuel (if done) can cause pressurization, so yeah fun stuff. All a good reason I like the old 50's and 60's stuff.

 

You just need to get your hands on the current information for proper troubleshooting.

They aren't better or worse than the old stuff just different with new ways of doing things and documentation hidden behind subscriptions.

 

That is the problem there is little to no information on it.

 

Honda will give you full access for $30/day. All the information you could ever want.

https://techinfo.honda.com/rjanisis/logon.aspx