John, I think your analysis makes lots of sense for a gravity fed fuel system (i.e. no pumps).  However, I would think that the EFI pumps would churn the water and fuel together pretty thoroughly. 

Yes the pump will mix it up pretty well; but it will separate out again in the line..

 

 

Ok, thanks, Al.  I had no idea how long it would take water to separate out from the fuel.

 

If  the water separates out from the mix fast then since my secondary injectors are down stream and below (gravity wise) – in fact the lowest part of my fuel system – that all plays with water in the fuel.  The water may have been more completely separated back out from the gasoline by the time it got to the secondary injectors .  Or to visualize a U shaped fuel line and imagine where the heavier water would be and the lighter fuel would be.  So even though the fluid might have been flowing – the odds are the secondary injectors saw more water than the primary injectors.

 

Ed