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.

Both my '88 and '87 are LH 2.2. The fuel pressure at idle is 36 psi. At full throttle (MAP near 0 psi) the pressure increases to about 42 psi, if I remember correctly. These cars use Bosch part #0280160292 which is rated at 2.5 bar(36.25 psi). Your '89 uses part #0280160294. It should be marked with its rated pressure. If it's 3.0 bar your fuel pressure should be about 44 psi at idle and increase with lower manifold vacuum(disconnect the vacuum hose).
The Bosch and Regina FPRs are not interchangeable.

Regards,
Bruce

Just what I needed to know. Thank you.

Chris,

I misremembered the figures. The pressures I gave were from the Bosch FPR on my BMW 325ic. It's FPR is rated 3 bar. The Volvos with the 2.5 bar FPR were 2 bar(29 psi) at idle and 2.6 bar(37.5 psi) with the vacuum line disconnected. Hope this hasn't caused excessive confusion.

Regards,
Bruce
--
'88 745, '87 744 in Virginia Beach

No problem. As it turns out, I may have been barking up the wrong tree anyway. Last night as I'm heading home. I get a call on the cell from my wife and mother-in-law. They had the car at the gas station and it wouldn't start at all, after filling it up. I got there and thanks to minimal tools in her trunk, I was able to loosen the fuel line at the regulator. I told my wife to turn the igntion on for a split second. Let's just say the "pump appeared to be working fine". I tested for spark - good spark. Still no start though. Sooooo...."Let's see", I'm thinking to myself - fuel being supplied (although regulator may not be allowing fuel to the rail, they usually fail the opposite way) - good spark - injectors must not be openning. I tell her to start cranking it and I whack the Radio Suppression Relay with a screwdriver handle. It instantly fires-up and purrs like a kitten. Now there's some high tech diagnostics for you.

As far as I know, it's got the original relay, as she has owned the car since new and we don't have ant recall of its replacement. $26 at Swedish Engineering which is right down the street from where I work. So it'd going to get a new relay and then we'll see where we stand.

As for the 2-3-2 code - That code indicates either an over-rich OR over-LEAN situation. It might be that the lack of injector operation caused the over-lean condition to be met??? We'll see if the code returns after popping a new relay in.

LH 2.2 or 2.4? If you run fault codes, then you've got 2.4

Try the items mentioned in the FAQ as common no-start issues on Bosch 2.4:

-rpm sensor
-radio suppression relay
-solder cracks in fuel injection relay

As for the FPR vacuum line, the FPR meters relative fuel pressure, not absolute. The pressure is metered according to the difference between fuel pump pressure and manifold absolute pressure; the vacuum line supplies the MAP signal. An internal spring controls the difference.