My KR-2 has a single Facet electric fuel pump in series with a mechanical pump on the 2180 VW. The Facet will will free flow fuel in the forward direction. The stock VW fuel pump has a shut off feature that will not free flow fuel if the engine is not running; the Facet cannot pump fuel through the non-running mechanical pump. I put a check valve in parallel with the VW mechanical pump to get fuel in the system, including the carburetor, for starting. The check valve also permits engine operation if the mechanical pump fails. Because I requested night VFR airworthiness , the FAA inspector required fuel flow measurements with each pump operating separately and the engine at WOT, max AOA and minimum fuel. Each test did require some discrete plumping changes firewall forward. Test fuel flows were 21 gallons per hour for the VW mechanical pump and 23 gallons per hour with the Facet. WOT and best power mixture at 13.6 AFR burns 5.3 gallons per hour. The Facet has a check valve built-in, the VW pump will not back flow and the extra check valve is not supposed to let fuel back flow; but after shut down the fuel in the system will drain back to the selected tank. The whole system, including the carburetor and gascolator, drains empty back to the fuel tank selected in about twenty minutes. How the carb float bowl and the gascolator empty is a mystery to me. If the fuel selector valve is set to off, the system will retain fuel.
Sid Wood Tri-gear KR-2 N6242 Mechanicsville, MD, USA --------------------------------------------------- Question Can you plumb 2 facet pumps in series and will each run the engine if the other fails. I have been trying to plumb them in parallel but its a real pain to get the tubing all bent correctly. Series would be much easier. It looks like the Zenith 601 was doing it at one time. Not sure they still are. Thanks. Craig
