When I turn the key to the Run position, (engine off) I hear a whooshing sound like the sound of air leaking from a tire. The sound is coming from my fuel pressure regulator.

I unplugged the vacuum hose, no noticable fuel odor.

I have been around these bricks for a long time and have never noticed this sound before. Is it an indication of a problem, is is it normal and I simply never noticed it?

I have an 87 740 with a noisey FPR. It sounds like a cat in heat.
YEEEOOOOWWOWWOOW.
My wife says I should replace the thing but I rather enjoy the sounds my FPR makes.
Not that I LIKE the call of a cat in heat, only that I am reassured that it is working.
Last month, my Fuel Pressure Regulator quit doing it's job and my Volvo barely ran at all.
Cleaning and lubrication is all it took to get it going again but it vibrates as the diaphram actuates so it makes kind of a siren sound.
Yes, I'll get another FPR soon. But, in the meantime, it is fun to watch the traffic part in front of me and dogs chase from behind...
YEEEOOOOWWOWWOOW. . .