I have a 1993 850 Volvo and it is in great shape. However, the car will kill when I drive down the road once in awhile. I have had it to the dealer and they can’t find the problem. They had the car for 3 months and 800 miles and it won’t do it for them and they can’t find anything on the diagonistics. I can eventually get the car restarted but it is definitely a pain. Help!
Likely fuel or spark. Get a spare spark plug. Next time it fails open the hood pull the spark cable off one plug, put the new plug on the wire and hold the plug’s threads tightly against the engine block and have someone try to start it. Watch for a spark. That should help pin it down
BTW you may want to hold the plug with a well insulated tool, or you could get an interesting shock.
Common problem with the ignition module. It will get worse, just don’t know how fast. It is hard to diagnose when it is not acting up. These are fairly pricey, too. But not hard to find. And, easy to replace.