Well...
Just taken it out expecting to find a split diaphragm or something as it was still running when I broke down, just no fuel. Found it's a scroll type mechanical pump so nothing really to break, if it runs it will pump.
Put it back together plumbed it back in, tested it and would you believe it... fuel coming out of the carb feed....
My only thought was that maybe the pressure relief to the return was wide open, but all looked OK,
Any ideas? Maybe an airlock?

