1999 Volvo XC70 cranks but no start

What you need to do is determine if its a fuel or spark problem that's preventing it from starting-Do below

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, cam and crank sensors and computer Note: If it doesn't apply disregard it.

Do you have gas in the tank? Sometimes one of the level sensors do fail so you may get a reading about having a 1/4 of gas when you are actually out of fuel? Start by adding a couple of gallons of gas and let me know what happens.