Thanks for everyone's help in my questions about center tank fuel feed. Yesterday I ran the engine long enough to fill the center tank (flew it) and the center tank fuel indicator came to rest around the mid- point in the new Skyport glass sight gauge.
I then drained the fuel out of the center tank into a gas can (from the line to the gascolator)and it measured about 5 gallons (center tank looked empty afterwards). Assuming this is the max volume I get when running the engine I thought maybe my tank is just 5 gallons, although labeled as 6 gallons on the cowl. I checked the old log books and it says the tank was replaced around 2001 with a new tank from UNIVAIR. The part number shows it as an aluminm tank which is supposed to be 6 gallons. Still a little mystery in the volume question (5 or 6 gal capacity)but at least I get 5 gallons of feed rather than 3 or 4 as I feared at first when the gauge never went all the way up the sight glass when "full". Couple conclusions so far: fuel pump appears to be pumping and I get around 5 gallons. The sight gauge I have acts like it should be for a different sized tank. One other weird thing is that the center tank seems to lose fuel volume if the plane sits a few days unused (i.e., the sight glass level goes down with time). My mecahnic thinks it might be fuel going back through the fuel pump as it sits. Is there supposed to be a check valve in the system? Does that happen to all Coupes? Thanks again for your help. Rich Green N3881H 1947 415CD
