Sorry Bill you'Ve confused me a bit there.
If thers no air going in then it is the pump. Mine has from what i can see no air going in or out so that would suggest that it is the settings.
I think you may have picked up on something i wrote on another thread about fitting a return line which unfortunately doesn't semm to have worked. In facy the problem of tilting vertical and the engine dying has come back. Any clue?
Thanks