Port tank not pulling diesel
OK - hers an update.
As a previous poster suggested, I opened the full port tank fill up and listened for air being sucked in - there was nothing I noticed.
Had some guys swing over in Marsh Harbour to look and brain storm - nice guys, Martin and Roger I think.
Roger offered that it can take a couple of days for tanks to equalize - we will see.
The feed to the racor is simple, both tanks feed into a T junction that feeds the primary racor. The return feed also goes into a T junction and splits to the 2 fuel tanks.
Martin noticed that the port side return pipe was considerably shorted than the starboard side so maybe less friction so a lot of fuel goes back into port.
After much discussion, while still anchored, I turned off the feed from the emptying starboard tank and just left the port tank open. I ran the engine for 35 minutes at 1200 RPM. Engine ran fine. I didn't want to do this on the open sea in case engine stopped at an awkward time.
So that is my solution - I will switch tanks at intervals - I should in a few days see the boat stop listing.
Thank you so much folks for all the suggestions - it really helped me to think things through!