1991 Volvo 740 Engine died while idling, won't restart

Hello:

My 18 year old son ust bought a very nice looking 1991 Volvo 740 Turbo. We test drove it, then drove it home 80 miles, no problem. Had it idling for about 10 minutes this evening to warm up the oil to change oil and filter when it suddenly died. Won't restart. I can hear the fuel pump, and it turns over strong. Won't catch. Took out a plug and it looked dry. Put plug back in, waited an hour, tried again - no start.

Any advice appreciated!