Honda EU2000i pulling too much fuel from extended tank

Yes - it is leaking out around the cap. So, there is an air leak, but in my previous setup there was as well. I have tried changing the height of the marine tank and it overfills when I place it above and fails to pull any when I don't. So, I should be airtight at the Honda cap and simply vent the marine tank?

Thanks for help with this. I thought with the primer bulb that I would be able to get the gas pull started and then maybe the Honda fuel pump would take over...

This setup *used to* work perfectly!