Darrel, For what it's worth...
I had some similar problems with my fuel system that plagued me for a while.
22 hp basic fuel system with Racor
would run no problem with boat flat. When I sailed with substanial heel (either side) Problem... Coming in at the end of the day I would start motor
... would run 10-15 minutes then quit.
Had to bleed it to get it running again. Seemed like air infultrated somewhere, something loose or moved? Trouble shot the system, tightening, changing, checking, cleaning
...feeling confident a thorough delibrate check out of the fuel system would trace the problem... No Luck! (Aux. tank with its own filters and fuel line into motor would run in all conditions no problem.) After I came up empty, 2 mechanics over a course of a year where brought to there knees ...alongside me! It wasn't until I changed every component of the system, except the tank(that would have been next) That it was fixed. We still don't know what the culprit was. But I have an entire
suspect fuel system as a spare!
In addition to the very good points indicated in the previous posts :
Check your vent line, sometimes little flying critters like to make nests blocking vent.
Check if screen
inside P.U. tube, if you have screen
check if clean. Older systems
may have had screens, newer ones I THINK??? do not. I removed mine.
Remove P.U. tube and check for hairline cracks (use magnifing glass) at upper connection caused by fuel sloshing about tank, especially if no baffles in tank.
Was told to run unused fuel return line to bottom of tank by fuel tank manufacturer,
(I didn't get why, but they thought it may make a difference!)
Hope your difficultees are not as ellusive as mine were! Good Luck!