There are two main possibilities:
Original no-start, December 2004. (1) In the Bosch LH-Jetronic series fuel injection systems, two fuel pumps are utilized: the main fuel pump (usually underneath the car, just behind the driver's seat) and the in-tank pump. The car will not start if the main fuel pump is dead, even if the in-tank pump still works. But, that in-tank pump will push fuel through the fuel rail and give you a false positive on the fuel delivery test at ignition "Start." Therefore, for the fuel delivery test, pull fuse 11 (check your owner's manual for correct fuse) for the in-tank pump and then run the fuel delivery test. That way, you can exclude the in-tank pump and see if the main fuel pump actually delivers fuel. For my original no-start, I got fuel delivery with fuse 11 in. That threw me for a loop and it took me several weeks to figure it out. Once I pulled fuse 11, I got no fuel delivery, which after making sure electricity was delivered to the old main fuel pump, meant the main fuel pump had died.
Second no-start, October 2013. (2) Got spark. Pulled fuse 11 and opened fuel rail to check for fuel delivery. Got fuel, meaning the main fuel pump worked. What next? Well, that meant there was a fault in the fuel injection delivery circuit. I checked for 12 V, with ignition "On," at the #1 fuel injector. Got 0.00 V. Next, I checked the feed wire (green/red) at the ballast resistor. I got 12 V, which implied a faulty ballast resistor. I replaced it and the engine started. (The fault was possibly dirt and debris that had collected in the tail end of the ballast resistor. The tail end is exposed, and when wet, the debris probably shorted across the individual resistors. This is an educated guess since I did not place the cleaned original back in the engine to see if the engine would start. After cleaning the original ballast resistor, the resistance checks on the original matched those on the replacement.)
More at Diagnosing No-Starts on Some 740/940 Volvos.