There is a spring in the system that acts as a regulator (IIRC) and you're supposed to pull it out, measure and make sure it's within the specified tension. I can't recall exact specs since it was my first time looking at the FSM for the 3rd gen (which I'm not a fan of BTW).
As far as I know the pump is driven by the motor via the oil pump chain (most people mistake as the TIMING CHAIN) and then the spring regulates the pressure (look at the oil cooler and follow the line to the front cover and the spring is below that "banjo bolt").
To make it easier, look at this diagram and find part #9. It should be the same for the FD.
Again, this is based on the little I saw in the FSM and I'm not an authority on this. Just trying to get more people to post in here with answers.