Mike, it seems like you are using the correct hardware. Have you tried bypassing the UAT? You can fly without it if you want to isolate it.

Check your pump fittings. On most pumps, the barbed fittings are pressed fit (into a plastic pump casing which makes absolutely no sense!). They can loosen over time, or if you pull on a line hard enough during assembly. It's very difficult to notice, but it will draw air pretty bad. Solution is to hysol in place, being careful not to obstruct ID. Went through several UATs before finding this problem.

Good luck,
David