Posted for "Larry Henney" <LHenney@dellepro.com>:

Fred,
 
My Dukes pump had to be rebuilt after running dry.  I ran it dry for
only about 30 seconds one time.  The little fins wore down alot in that
very short run.  Perhaps one reason your prime is taking longer than it
should is because your pump is worn.  That pump and fuel line should be
wetted continuously while sitting in your hangar for weeks.  Perhaps a
tiny air leak is permitting the pump and line to fill with air.
 
Also, it is desirable to have the elevation of your fuel lines at
constant or descending levels from the tank to the engine.  If you are
only using wing fuel then a pump high on the firewall would be better
located down low.  This would eliminate some of the suction required of
the pump.
 
Also, I would not add a priming pump to prime the priming pump.  This
add's connections and additional failure possibilities that increase
risk.  I am a firm believer in no more than an electric pump and a
gascolator or filter in the main fuel feed line.   In Short, I'd recommend rebuilding and rehanging the Dukes pump at a
lower location on your firewall.
 
Good Luck,
 
Larry Henney
LNC2 420 hrs
Granbury, TX