Jeremy, I had exactly the same problem on my 3.9, put a live from your battery to the pump, it will probably work! I replaced both of the Lucas Bosch relays, same problem.
These deteriorate on the shelf when new, the bakelite type thingy inside disintegrates. The Factory use Chinese made relays, I replaced mine with them, no further problems.
Moral of the story : not all Chinese stuff is cr*p!
