Performed the fuel flow test to insure that the engine will get sufficient fuel in a climb attitude. Elevated the front with the shop hoist and blocked under the main gear wheels. Removed the fuel supply line at the inlet to the fuel pressure regulator and fed it to a 1 gal container through a short 3/8" hose. Connected the left fuel line to a 2 gal container with fuel. That container was at the same level as the bottom of the wing mounted fuel tank. Turned on the fuel pump and recorded how many minutes to fill the 1 gal container. It took 3 minutes 45 seconds which means that the fuel flow is 16 gal per hour while the fuselage is in a climb attitude.
The engine could use up to 9 gal per hour at full (100 hp) power using the formula 0.55 lbs of fuel per hp hr.
Fabricated a new flow restrictor for the fuel vapor return line with a #63 drill (0.037" dia) which flows 4 gph back to the fuel tank at 9 psi fuel system pressure. When the engine is running the system pressure is lower and less fuel would be returned to the tank. 4 gph is a maximum possible fuel return.
Fuel flow requirement is for the fuel system is to provide 1.25 times the full power fuel need. 9 gph x 1.25 = 11.25 gph fuel system requirement. The system flows 16 gph - 4 gph returned to the tank = 12 gph available for the engine. Meets fuel flow requirement.
Fuselage set at 15 deg angle for flow test
Main gear on supports for 15 deg angle
Fuel flow connection at inlet to thje fuel pressure regulator feeding 1 gal container
