I'm trying to trouble shoot an occasional no-start / hard-start problem in the mother-in-laws 740/B230NA/137,000 miles. Here is what I've observed so far:

Starter cranks OK. Tach twitches during cranking regardless of whether it starts OK or not. Fuel pump runs for short spell when key is turned-on regardless of whether it starts OK or not. It has failed to start for her on a couple of occasions in the last few days. She left it for a couple days with a good Volvo independant mechanic and (you guessed it), it started every single time for them. I notice that even when it starts OK, it smells very rich at least during the first couple minutes of cold running. Once the car starts, it idles and runs down the road fine. I retrieved the one and only fault code of "2-3-2" which translates to various causes depending upon what publication you read, but the 700/900 FAQ's say "Fuel trim (lambda control) too lean or too rich at idle - If too rich: high fuel press., leaking injector".

I can clear the fault code and then run the engine for a few minutes which causes it to return. I've looked and listened carefully for vacuum leaks and it all looks good and tight.

My gut feeling says "Fuel Pressure Regulator", so I want to check the pressure, but I've got a couple questions:

Does this car have the LH 2.2 or 2.4? (1989 740 NA)

What is the proper fuel pressure at the rail?

Does it sound like I'm on the right track? (Besides possibly the O2 sensor itself, I'm not suspecting any other components yet as I only got the 2-3-2 code. Nothing to indicate bad AMM, etc.)

My wife drives a reliable 90 740 Regina. (Oh no, don't open that wound again!) Does it operate at the same pressure? Can I borrow the regulator from it?

And something I've always wondered about these cars - Why is there a vacuum line to the pressure regulator? Is the amount of vacuum supposed to vary the pressure?

I know this was a mouthful, but I believe in detail. Thanks in advance for any help, suggestions, or opinions.