Back when my fuel system was completely stock, the fuel pump would come on real loud when I turned the key on for about 30 seconds, then it would go quiet, and run normal. Now, after I installed a fuel pressure regulator, it runs loud all the time...any thoughts as to why it changed?
Have you checked the fuel pressure with a test gauge? If it is set incorrectly, the pump would run all the time.
Check fuel pressure:
The local auto parts store may rent or loan a fuel pressure test gauge if you don't have one.
Disconnect the vacuum line from the fuel pressure regulator. Check it for evidence of fuel present in the line by removing it and blowing air through it. If you find fuel, the fuel pressure regulator has failed. Reinstall the line, cap the open end and stow it out of the way.
Connect fuel pressure test gauge to Schrader Connect fuel pressure test gauge to Schrader port located just behind the alternator.
Turn the ignition switch on & start the engine. Observe the pressure : you should see 37-41 PSI at idle.
Turn the ignition off, reconnect the vacuum line and disconnect the fuel pressure test gauge. Watch out for squirting gas when you do this.