In the rebuild of my PA-12 this summer I installed an Atlee Dodge 30 gallon tank in the left wing, the right wing had a standard 18 gallon tank. My fuel system selection has four positions off, left tank, right tank, and both. I have always kept it on both. When I flew the plane on a two hour flight the sight gauge on the right tank indicated that it emptied first while the left tank (Atlee) stayed full even though the fuel selection was on the both position. And in fact when I filled up the tanks the right tank was almost empty while the Atlee tank was almost full. After the next flight, a short one, looking at the wings it appeared that gas was running out of the left (Atlee) tank while in flight. Trying to figure out what happened we determined that the difference was in the fuel caps. The old tank had the vented cap with a tube at a right angle pointed into the wind, while the Atlee tank had a cap with two small vent holes one in each side of the cap. This we concluded created positive pressure pushing gas from one tank into the other. We were told by Steve at Atlee?s that both tanks must have the caps with the tubes pointed into the wind if it has a 180hp which it does. Make sense??
PA!2
PA!2
you should have known to install the ram-air vented caps on BOTH tanks.
