REFLECTOR: Fuel System -- Return Fuel Flow

[Brian Michalk]

In my arrangement, I an using electronic fuel injection, with my fuel 
rail running at 45PSI.  I have a Bosch electric pump delivering what I 
think is .7 gpm (I need to verify this), and a mechanical positive 
displacement pump delivering 1.7gpm.

My fuel pressure regulator returns the fuel to the sump tank, which is 
also where the feed line is for the fuel pumps, so the fuel circuit is 
sump->pumps->FPR->sump.  Since I'm fixed gear, my sump is a little less 
than five gallons.

My question is, what are other people doing for their fuel return 
configuration that are using actual regulators.  The vapor return system 
on some of the aviation pumps returns very little fuel, I believe, so 
it's not the same thing.

Is a five gallon sump big enough?  Will it fill up with foamy fuel 
vapors?  This is avgas, not automotive fuel.