My brick is a 1990 740 wagon with the Rex/Regina ignition, single fuel pump in the tank, AT, 187,000 miles. I've driven this wagaon 10,000 miles since I bought it November 1, 2005 and its generally started easily and runs strongly. Plenty of acceleration (for a na 230!), no hesitation, no stalling, smooth idle, 25 mpg. Three or four times it has stalled when warm starting, but a second try started it and it would idle and run well. Two days ago I had a very difficult time with warm starting. Start and stall, start and stall, usw. Finally after prolonged cranking it started and idled poorly for 5 or 10 seconds, then smoothed out and ran and idled well. It would restart after I turned it off if I tried immediately, but after sitting for 10-30 minutes, again hard to restart or no start at all. Cold starting is now the same story, hard start or no start

The check engine light didn't illuminate. A visual inspection did not reveal disconected electricals or vacuum hoses. So I first tried switching the FPR with another known good FPR I had available - no change.

This Volvo has the OBD-I system so I tried the procedures discribed in the FAQS to test the fuel injection system and the ignition system. The ignition system tested code 1-1-1 no faults. The fuel injection system set the code 3-2-1, FAULT CONDITION: Signal missing to/from cold start valve SOURCE OF FAULT: Radio suppresion relay. Progress I thought! I switched the radio suppresion relay with the electic radiator fan relay. No change and OBD set the same fault.

Next I tried the Ignition System Component Activation Test. As part of the test I could hear and feel the RSR activate and the 4 fuel injectors activate, but I didn't hear or feel the cold start valve activate. I pulled the plug from the cold start valve, attached my VOM and reran the SCAT. No voltage at the plug.

Replacing the RSR is cheap, $56 from the dealer, if it will fix my starting problem. Can this relay fail for the CSV only? I know that I switched relays, but I'm certain that they are orginal and they may have already been switched to fix a problem in the past! Can another failed component in the starting chain set this code? I pulled the fuel pump relay (I don't have another for testing) it's very clean inside and out, and I couldn't see cold solder joints or cracked solder on the circuit board.

I ran out of time today, but I do intend to run the System Sensor Signal Test in another 2 or 3 days.

I hate the idea of replacing parts without a certain diagnosis. But what I really, REALLY hate is the possiblity that there is a broken wire or loose connection. Difficult and tedious to track down! I don't want to reinvent the wheel and I'm hoping that a BBoarder will have an idea about what my next move should be.

...it's a known condition resulting from a wiring change to the cold start valve.

Hate to say it, but your symptoms sound like an end-of-life Regina Fuel pump. This is based on two recent threads here, one by Art Benstein. I can't recall the other one, but he chased it for a long time.

Just googled regina pump benstein and found the other thread from Haroon here, with Art's comments and a link to his pump replacement photo sequence.
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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Very interesting. I bookmarked Art's photos four weeks ago when the link was posted here on the BB! The pump has been intermitantly noisy and I thought to myself that one day I should replace it before it failed. I'll be doing some more troubleshooting tomorrow and I'll report my findings.