[JimC]

Thanks! I think that solves it - I was wondering if it was a turbo/non turbo thing.

Also, I don't have the same return to the main from the aux tank that he describes. My 340 does - the aux tank empties in about 1/2 the time that the fuel burn would predict (the remainder is sent to the main tank, as in the NA 337s.) In my turbo yesterday, I ran my 18 gallon aux tank dry after (fuel flow x time) showed I'd burned 17.6 gallons of fuel. That's close enough for me.


I also came up with a simpler diagnostic test for anyone who's curious:

While safely on the ground before engine start, set both engines to feed from one main tank. Turn on the electric pump for that tank's engine. Does the fuel flow for one engine rise, or does the fuel flow for both engines rise?

BTW, I always like to try to say "electric pump" instead of "auxiliary pump." It confuses some people when mixed with "auxiliary tank."