OK so here is an idea I have been kicking around that reads fairly directly on this thread. Has anyone put a pressure sensor in the header tank? If my math is correct it should read ~1.5 lbs if there is fuel in the tanks and the filters are not clogged. If the supply to the header tank is starved for any reason (empty tank or restriction in the flow) the pressure will drop to zero or less depending on the fuel pump. This would of course be true for normal flight conditions as it would be effected by relative Gs.
Comments?