Hey everyone, quick question regarding fuel pressure on a cold engine. On Cayenne base 3.6, when the ignition is on but the engine isn't started, should the high-pressure fuel pump pressure be the same as the low-pressure fuel pump?

I'm experiencing long cranking only on a cold engine, and I suspect the HPFP is failing. Sometimes the engine starts after long cranking but immediately turns off. However, if I try starting it again, it starts right away. No codes.