WHERE IS THE FUEL PRESSURE REGULATER AT ON A 2001 GMC JIMMY?

On a 2001 GMC Jimmy, the fuel pressure regulator is integrated into the fuel rail. It's not a separate, easily identifiable component. You'll find it on the fuel rail itself, usually near the end opposite the fuel filter side. You'll likely need to look closely at the fuel rail to identify the regulator; it's often a part of the rail's casting.