My '94 940 is driven daily. Yesterday, I drove for about an hour then parked for about 20 minutes. It cranks, but won't start. The former owner (2 mos ago) said it had a history of developing a bad fuel relay - she even had a spare in the glove box. Anyway, I've also got a 1991 and switched this sensor with that car's sensor knowing it was good - that wasn't it. I've ruled out both fuel pumps as the culprit and have ordered new plug wires, cap and rotor I'll install tomorrow. I plan to verify that it has spark this afternoon. My concern is that while I may learn it doesn't have spark, I'm unsure if that will isolate the coil to be the problem as there seem to be so many relays and sensors with a volvo. Please share you wisdom, hunches, insights and instincts in solving this problem! I need your help.
Brian

Check this out in the FAQ's, basic troubleshooting tips, find your symptoms and look for the possible solution(s).

http://www.brickboard.com/FAQ/700-900/EnginePerformanceSymptoms.htm#NoStartFrequentStallorHesitationBasicDiagnostics

Have you checked the rpm sensor?
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Bob K

Please describe the location of the RPM sensor and I will investigate that possibility.
Brian

RPM sensor is on the upper-passenger side of the transmission bellhousing immediately behind the engine. You probably cannot see it but you can feel it. The connecting wire snakes across to the driver's side to a connector in the harness on the firewall. Typical problem would be the wire degrading where is passes behind the engine. 10mm socket and medium extension is all you need to replace it.
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Bob K

Here is a thread on recent no start. Yes, I hate the thought of stalling out but it is probably no worse than anything else on the road. My problem was a FP relay and then a crank sensor. I carry spares in four out of the five cars. Won't help my wife though.

http://www.brickboard.com/RWD/volvo-983921.html?show_all=1
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Tom F. Three Bricks, maintain two more.