Wow, you've had a few Volvos.

Next time it absolutely won't start, have an aerosol can of ether, or other flammable, handy with a straw to direct the flow. Remove the vacuum hose which connects the fuel pressure regulator to the manifold, and spritz a second's worth of flammable into the manifold through that nipple. Put the aerosol can safely out of the way and reconnect the vacuum hose and try to start it, to determine if you are missing spark or fuel. If you notice the hose is wet when you first disconnect it, replace your fuel pressure regulator.
--
Art Benstein near Baltimore

Experience is something you don't get until just after you need it.