Dave,
These were flights 72-77 on the Hunter. The tanks have not been opened since initial build 3 years ago.
I use BVM Hi-Flow clunks and Skymaster style screw-in fuel tank fittings, going to a MAP 4oz Air Trap.
I have experienced the same effect on my Ultra Flash (Jet-Tech main + saddle tanks with the same installation fittings) and ended up replacing the Air Trap.
I run pump kerosene that I add algicide to every time, and it is filtered twice coming out of my Jersey Modeller tank. I even replaced my fuel caddy fuel filter last year after the problems with my Ultra Flash.
The only thing that I don't do is filter the fuel as I pump it at the gas station, or when I decant it into my main fuel caddy.
Any other thoughts on maintaining a clean fuel system are welcome.
Paul