If it's a brand new engine, the carb needs to be primed. Take both needles out and squirt fuel in the holes. Let it sit for a minute or two. Squirt fuel in the holes again. Run both needles all the way back in until they stop. Now back them both out 1.5 turns and start it. Tune accordingly.

I can't see a brand new engine having gummed up diaphragms or dried out diaphragms. It's never had any fuel through it. Shouldn't need to replace brand new pump diaphragms. [:-]

Try priming it first.