Success! I put 5 US gallons of premium auto fuel into the tank (less than a quarter full) and let it stand over night to check for obvious leaks in the bottom portion of the fuel system. The next day I disconnected the 5/16" fuel inlet hose at the engine's mechanical fuel pump and rigged a temporary fuel catching pitcher in place. Then with fingers crossed and a fire extinquisher in hand I turned on the electric fuel pump. It quickly stopped chattering as it pulled in fuel and discharged it through the hose into the pitcher. The only downside is that I couldn't get any flow out of the Primer Bulb which is used to pump the Fuel Tank Sump over the side. Maybe it needs priming, or a fuller Fuel Tank?
