7AC wing tank

[Autogateman]

My Champ has a 13 gallon Wing tank on the right side with a ball valve inside that you turn on to drain it. I was told that it just drains into the main 13 gallon tank. I was looking at the fuel line today and it tees into the main line close to the bottom of the firewall below the main fuel shut off valve. He told me I had to be in Level flight or have the rear jacked up for it to drain because the port is in the front of the tank. Today while flying I opened the valve for a while but never saw any changes on the fuel gauge of the main tank. Does it actually backflow into the main tank or does the engine run off of both tanks simultaneously when the valve for the Wing tank is open?

 

[Bob Turner]

It should fill the main. Your cap, at the very least, needs to be vented. Even then you might need a high G pullup to start the flow.

Get a non-vented cap (Spruce, $20) and a carbide drill, and some copper tubing, and make a snorkel cap to better pressurize the tank.