Re: Pietenpol-List: Air Bound Fuel Lines - was Weber Carb
Posted: Wed Apr 06, 2005 7:56 am
Original Posted By: _TBYH(at)aol.com_ (mailto:TBYH(at)aol.com)
Subject: Re: Pietenpol-List: Air Bound Fuel Lines - was Weber CarbFellow Piet lovers,I'm a little reluctant to chime in here, but I must relate my experience with the Cessna 150 fuel system. This will support the air-bound fuel line possibility.The C-150 fuel system is almost as simple as it gets. It has 2 wing tanks with 3/8 inch lines that Y together, an on/off valve, a gascolator -- that's about it. I ran the plane low on gas once and took off with about 1/4 tank (or maybe less) and must have unported the fuel pickups in the tank. At about800 feet AGL the engine shut off. After that it ran just barely enough to get me turned around and back to the airport.Here the story begins. I shut off the fuel valve and removed the line at the carburetor. When I tried to drain the tanks into a gas can nothing came out. After blowing into the line (by mouth) and hearing bubbles go into the tank (or tanks), the fuel began to flow. I drained the system and shut off the fuel valve, then put 5 gallons of gas in one tank. Turned on the valve andnothing came out of the hose to the carb. A slight blow of air into the hose and all 5 gallons drained from the tank. Ah, the hose must have a flap init. Took the hose apart and inspected it carefully. Blew into both ends of the hose. Could not detect any defect at all. Disassembled the gascolator. Found nothing wrong. Repeated the above on the other wing tank. No flow. Blew into the line, all 5 gallons came out. Took the whole system apart -- line by line, fitting by fitting, looking for something acting like a check valve. No problems found at all. Put the whole thing back together and flewit for 4 more years, before selling the airplane.I still don't understand it, but I certainly believe that you can have an "air-bound fuel line."If anyone can explain how my experience is possible, I would like to hear it. It certainly seems like gravity would win, but it didn't.Dan HopperWalton, INRV-7A - flying, Pietenpol - still drooling over the plans.In a message dated 4/5/05 6:54:14 P.M. US Eastern Standard Time, gcardinal(at)mn.rr.com writes:Dale Johnson and I had the same problem. Engine would start and run fine but the fuel bowl would empty out. The problem was an air-bound fuel line.The fix was easy. Just lift the tail as high as possible for a minute or so until the air bubble worked it's way back up to the tank.No problems after that.Greg Cardinal----- Original Message -----
Subject: Re: Pietenpol-List: Air Bound Fuel Lines - was Weber CarbFellow Piet lovers,I'm a little reluctant to chime in here, but I must relate my experience with the Cessna 150 fuel system. This will support the air-bound fuel line possibility.The C-150 fuel system is almost as simple as it gets. It has 2 wing tanks with 3/8 inch lines that Y together, an on/off valve, a gascolator -- that's about it. I ran the plane low on gas once and took off with about 1/4 tank (or maybe less) and must have unported the fuel pickups in the tank. At about800 feet AGL the engine shut off. After that it ran just barely enough to get me turned around and back to the airport.Here the story begins. I shut off the fuel valve and removed the line at the carburetor. When I tried to drain the tanks into a gas can nothing came out. After blowing into the line (by mouth) and hearing bubbles go into the tank (or tanks), the fuel began to flow. I drained the system and shut off the fuel valve, then put 5 gallons of gas in one tank. Turned on the valve andnothing came out of the hose to the carb. A slight blow of air into the hose and all 5 gallons drained from the tank. Ah, the hose must have a flap init. Took the hose apart and inspected it carefully. Blew into both ends of the hose. Could not detect any defect at all. Disassembled the gascolator. Found nothing wrong. Repeated the above on the other wing tank. No flow. Blew into the line, all 5 gallons came out. Took the whole system apart -- line by line, fitting by fitting, looking for something acting like a check valve. No problems found at all. Put the whole thing back together and flewit for 4 more years, before selling the airplane.I still don't understand it, but I certainly believe that you can have an "air-bound fuel line."If anyone can explain how my experience is possible, I would like to hear it. It certainly seems like gravity would win, but it didn't.Dan HopperWalton, INRV-7A - flying, Pietenpol - still drooling over the plans.In a message dated 4/5/05 6:54:14 P.M. US Eastern Standard Time, gcardinal(at)mn.rr.com writes:Dale Johnson and I had the same problem. Engine would start and run fine but the fuel bowl would empty out. The problem was an air-bound fuel line.The fix was easy. Just lift the tail as high as possible for a minute or so until the air bubble worked it's way back up to the tank.No problems after that.Greg Cardinal----- Original Message -----