2000 S70 with 85K miles. Suddenly decided not to start, cranks fine. Checked spark, OK. Pulled the plugs and they were flooded with fuel. Dried and oiled the cylinders and am now looking for a cause. Does anyone know what the fuel pressure should be with the engine off? I can't find the specs.

 

The fuel pressure should be about 35-45 running. When you shut it off it will rise a little then hole.
But You might want to look for a bad Vaccum line at the regulator.It could be a bad Injector/leaking.

Another possibility that happens from time to time is the lifters bleed down. Then when you crank it the engine floods before the lifters pump up.

 

It has 55psi with the engine off. I haven't tried starting it yet because I don't want to de-flood it again if there is an obvious problem. Where is the fuel pressure regulator on these? It is not on the fuel rail and I don't see it in the hard line running down the front of the engine. If it is vacuum controlled I would like to try applying vacuum to see if it is working.

 

It is on the bottom side of the fuel rail. It is between I believe cylinders 2 and 3 injectors.

 

I see what appears to be a pulsation dampener on the bottom of the fuel rail between the #1 and #2 cylinders. It has no vacuum line. I also do not see a return line and I am begining to suspect that this is a returnless fuel system.

 

Yes then you have one without the return line and vaccum line.
That is the fuel pressure regulator.