1998 S90 175,000 miles.
Got in my car to go to work today nothing out of the ordinary. Stopped by the post office on my way to work, when i rolled down my window to drop a couple letters into the mail it kind of smelled like gas. I was only a mile or so from work so i went in to work shut off the car, opened up the hood and didn't see anything (i should have kept the car running). When i went to go get some lunch i turned on the car and noticed it was running pretty rough, this time i left the engine running and saw what looked like a ton of gas coming off the rail where the fuel pressure regulator is. I looked around and couldn't tell if the leak was coming from the pressure regulator or from the rail. I'm thinking the only way to really tell is to pull off the regulator and rail to take a look at them? If there's a better way please advise. Also how dangerous is it to drive with a leak like that? I'm thinking hot engine with gas flowing out at a pretty good clip isn't good. Also could this be a sign of a bad fuel regulator. I tried to look up signs of a bad regulator and didn't really find to much.

 

Leaking end cap of fuel rail is a known issue. Some people have tried to fix the cap, without success.

Volvo redesigned the rail, by correcting the issue of vibration isolation. You would need the redesigned unit, which is about $ 130. Try Tasca Volvo.

Absolutely do not run the engine with this problem -- fuel can reach hot areas of engine and start a fire...