I've got a 5hp Briggs and Stratton Rototiller engine with a Pulsa-jet carb. This particular Pulsa-jet does not have the check valves in the pick-up tubes. Not required. All the parts are clean, the screens are clean, there is fuel in the constant supply cup. The needle valve isn't damaged and the jet is clear and looks fine. It has all been cleaned with carb cleaner. My problem is, it runs rich even with the needle adjustment valve turned all the way in. I can't figure out why it is doing this. The diaphram isn't torn but shouldn't have anything to do with it running rich. The diaphram just works the fuel pump. Any ideas what's causing this thing to run rich. It's as though the chock is on which it is not!:confused::rolleyes::(

Its very possibly the needle valve is bad or the seat which the needle valve seats into witch is overlooked many times.

Any tweak for the air adjustment to balance the "running rich"

It ended up being the diaphram was stretched. I replaced it and it ran like a champ!

Glad you found the problem