My first thought is that there is a main seal issue on the crank seal behind the gear case.
When the balance gear went was the gear case still full of oil? I wonder if that seal went and sucked all the oil through the engine causing the balance gear failure in the first place. With the pulse tube off of the gear case you should be able to feel a pretty strong pulse coming out of the engine, if not it is not likely that seal. It is possible to get it out without breaking the bottom end apart, its just kind of a pain.
Other than that, about all it can be is an issue with the way the lines are hooked up, an issue with the way the gears are installed, or the fuel pump needs a rebuild kit.