Thank you for your reply sir. Found the answer in the JD tech manual. It is a self prining system and the the filter/pump is primed by relieving the air back thru subject hose to tank.
Personally I think the Deere filter is quite rinky-dink and find it difficult to justify $8-$9 for a replacement element.
Whatever works.........
But that return line will be mighty important if you run out of diesel and you do not have to bleed the system to get running again (I assume that is why the cheaper filter without the extra line was indeed 'cheaper').
Good to find out what that extra hose is for. /forums/images/graemlins/wink.gif