Make sure the o-ring for the high pressure line is intact.
The system holds just a couple of quarts IIRC. I flushed mine with 3 quarts not long ago. I disabled the ignition (unplugged the coil's electrical connector) and cranked the engine with the low pressure line disconnected. The LP line to the cooler was run into a bucket (if you do this, plug the low pressure port on the pump or you'll dump your fresh fluid directly from the reservoir onto the ground, without it going through the system).
Getting the pulley off was a pain. I had a buddy with the MAC Tools puller, that made life easier, I looked at the puller at Auto Zone, glad I didnt use that. Yes the high pressure line O ring, muy importante, it comes with an O ring, and a little teflon ring to replace the fact. one on the HP line, cut off the old one, throw the new one in a glass of hot water for a minute, slide it down a punch to work it open some, then pop it over the threads on the line, then O ring, then install. It wasnt so bad. Pulley sucks.