[v8volvo]

Check the glow plug fuse. It's screwed in to the bottom of the relay, a big flat blade style fuse on the bottom side of the relay (on the driver's strut tower). Could have burned out.

If it is cold out and your plugs are all dead, or if only one or two are working, there is no way it will ever start. If there is smoke then you know you are getting fuel at the injectors. The timing could jump on shutdown -- had that happen once on an old Rabbit diesel, mysterious but it did happen and I had to retime the motor before it would start. An easy check would be to see if the notch on the back of the injection pump pulley *roughly* lines up with the hash mark on the rear flange of the injection pump when the crank is at TDC (sight through the hole in the bellhousing under where the pump is and watch for the "0" mark on the flywheel to appear in the opening and line it up with the pointer inside the hole). If the marks on the pump are anywhere close when the crank is at TDC then it should be OK, at least it should be where it was before when it ran. If they are even as much as one tooth off -- let alone two or three -- it will not start at all. All you need to do this check is a 27mm socket for the crank bolt and some patience, no special tools, so it would be worth checking if you have time.