Originally Posted By: TFB1
Most systems in approx the last 10 years don't have a fuel pressure regulator but instead have a fuel pressure sensor... These systems regulate pressure by varying the voltage to the pump, vs having a mechanical regulator and constantly running the pump at battery voltage... Plus is there is no fuel return line to the tank and pump supposedly lasts longer as it's only pumping what's necessary, instead of constantly circulating the fuel...
My understanding is that returnless systems are an answer to recent EVAP regulations: Returnless systems lack a return line, which eliminates a line and lot of connections, all of which are potential sources of fuel/vapor leaks.
As for the OP's question, I'd expect that most fuel-pressure problems would be very likely to be flagged by the OBD-II system before any symptoms would be felt. I'd be expecting an illuminated MIL with a P01xx DTC.