I hope somebody can help me here. About a couple of months ago, my 240 would drive for about 10 minutes and then stall out and not restart for a couple of hours. This was a problem for a couple of weeks. During this summer I didn't drive it at all for about 2 months. I just took it into my Volvo guy and he couldn't find anything wrong with it - he drove it around, it was fine, he let it run for a long time, it was fine. Nothing to fix. I am going to pick it up, but am a little hesitant to drive it around (I like the exercise I get when I have to walk home from wherever it happens to die, but man, it would be so much easier if I didn't have to!). Does anybody know what might be causing it to die like this?

my 88 240 wagon had simular problem
and it turned out to be a bad ground wire
on the fuel rail

Corroded fuses or bad solder joints in fuel pump relays most often (but not always) cause the engine not to re-start after it is shut off, not die while going down the road. The infamous rotten wiring insualation used on most Volvos made in the 80's is highly suspect in your case unless the wiring harness has been replaced. If it dies again, try moving the grey wiring plug at the left-center of the firewall just a little and try restarting it (this grey plug is just behind the transmission dip stcik if you have an automatic). Or, while it is idling at your house, do the same thing and see if it dies. One of the wires coming out of that grey plug carries 12 volts from the ignition key switch to the coil. If it shorts out due to rotten insualation, the engine will die. The wire in question is a fat brown one coming out of the grey plug and going to termial number 15 on the coil. Also, carry a short jumper wire with alligator clips and if it dies, pull the wire off coil terminal 15 and connect the jumper to it and the positve battery post. Crank it over and see if it starts. jp

It may be a faulty ignition coil. I think I've read somewhere that under high underhood temps, a bad coil may cause problems.
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1980 245 Canadian B21A with SU carb and M46 trans

See if the problem goes away if you fill the fuel tank completely full. If it does you may have a bad hose inside the fuel tank feeding the in-tank pump. Easy fix.

Or relay.

Something is failing when the engine gets up to operating temperature. The other thing that commonly causes this kind of intermittent problem is a failing hall sensor in the distributor.

I would definately try the fuel pump relay, located under the instrument panel. The solder deteriorites over time tending to cause intermittent connections when warm. The relays aren't very expensive if bought through FCP Groton or the like.