Could this be vapor lock?

John, you could always go with mechanical as primary with an electric as a backup. That's how I have it in my M715. I'd recommend a filter before the pump (whichever style you go with) and one before the carb.

Stan

 

If you have a filter with return mounted between the pump and carb it could be just cycling and not sending any fuel to the carb. Had this happen on my buddy's flatty. bent the rubber return line and zip tied it to cause enough restriction to push the needle off the seat.