Made up a temperary fuel tank and ran the fuel pumps to circulate fuel through the system. One small leak at the fuel filter that needed tightning. A lot of vapor bubbles in the return line, but that was expected. These bubbles are a result of the pressure drop when the pressurised fuel is returnde to ambiant pressure a the engiine pressure regulator. Must not reingest the bubbles.The flow rate looks like its moving at about 3 mph.