The regulator regulates the pressure to a certain determined pressure.
The relief valve is I the fuel pump itself that will retain pressure when it is at rest
February, 5, 2013 AT 3:14 AM
Probably. Never heard it called a relief valve like they use in an oil pump. Chrysler has had extremely little trouble with their fuel pressure regulators. I've only read about one ever leaking, and I had one with a cut o-ring that caused a long crank time for the engine to start. The part cost five cents for that repair.