Leaving the drain open, when I turn on the boost pump, the flow out the drain valve stops.  Turn the pump off and the flow starts back up again.  It's as if the pump was working backwards.  I switched the power leads and no difference. My previous pump would flow like gangbusters out the gascolator drain when I did this.  The new pump went in exactly the same way as the old pump, but it's 20 or so serial units newer.  When looking at the fuel dump overboard port, I have fuel going into the right side and exiting the left side.

Ed,

 

Seems I recollect 2 dump ports 180 degrees apart, one sealed with a plug, the other used for a drain.  Anyway, mine is forewall forward and feeds from the left with output to the right.  Maybe the pump is backwards.