Posted for Don Skeele <dpske@wvi.com>:

Angier,  As I see it, the cross feed line/valve could present problems of loosing suction in a wing tank at low fuel levels if one wing is a tad low, or the first tank to go dry might leave usable fuel behind in the other tank. Of course the flow lines MUST go into the day tank above the overflow level or you could syphon backwards thru either Facet pump.. For one opinion, keep the pump lines separate and plan to keep a minimum of say, 5 Gals in the day tank to allow for an expeditious landing if you lost both pumps (power failure). Same old principle, keep it simple.. Don Skeele  235/320   (503) 769-2563