1986 Volvo 740 won't start

Hi cfanning, Welcome to 2carpros and TY for the donation

Do below to determine if its fuel or spark issue and report back with some testing results

Get a helper disconnect a sparkplug wire or 2 and ground it to the engine atleast 3/16 away from ground-have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs, coil's resistances, cap and rotor, distributor pick-up coil, ignition control module, power stage, cam and crank sensors and computer Note: If it doesn't apply disregard it and keep testing

As I stated in the original question: it is getting both fuel and fire; this is why i'm so baffled. The fact that it happened so suddenly is also confusing. Since it was running, then just refused to start, whatever the problem is must have happened in the few hours it was parked. What else should I try?
Thanks,
chris

If you're getting a snapping blue spark, the correct fuel pressure and injectors are pulsing it should fire up-unless there's a problem with the valve and ignition timing. Which is very unlikely to happened being parked a few hrs-Try checking the timing belt if its still intact could have slipped a notch or 2-If okay go back and recheck the other two-

The timing belt is still intact, but in pretty rough shape. I'll go back and see if it might have slipped. I'll let you know how that turns out.
Thanks for the help,
chris

So after much head scratching, I discovered (almost by accident) that gas was coming out the intake manifold backwards as well as to the combustion chamber. A couple of vacuum lines later, I figured out it was the fuel pressure regulator; it was indeed getting fuel, just too much of it. Replaced it pretty quickly and now it's running just fine.

I'm glad that you have resolved the problem and you coming back with the fix so that everyone that pays a visit with similar problem will learn from it-TY