Mike:
I have been reading this thread for a couple of weeks and I want to put in my 2 cents. I have the Creek Staduacher and have a Moki 1.8 on it with a 24 oz fuel tank mounted at the CG. My engine was responing like yours (no response after 2 turns out on the needle) I put a pump on it and it didn't help. The engine would peak out at 2 turns and never lose RPM no matter how far out the needle was turned. The problem was the fuel tubing supplied with the tank is the same size as a 10 OZ tank. I bought the next size up brass tubing and a larger clunk and installed large tubing from the carb to the clunk. The problem is that only so much fuel will travel through that small tubing no matter how much you push it (or pull it). It's basic hydraulics. With your tank mounted at the firewall you should not need anything but muffler pressure.
If the pump doesn't work you might give it a try. I think the larger tube should be used on anthing larger that a .90 size engine.
Maybe only 1.5 cents worth, but to you it is free.
Hal Lockett