If you were running on only the main fuel pump, it should be hot. Now that you have a running pre-pump is it still heating up? Is the pre-pump running?

BTW that pump uses the gasoline around it for cooling, so running consistently in the lower 1/4 of the tank can damage it over time.

Have a helper listen at the gas filler tube - hold the "Unleaded Only" little flap open. The pump runs a few seconds when the key hits Position II, without starting the engine.

The same thing can be done for the main pump. It is mounted such that it can be touched by reaching hard to the rear and upward in the LR wheel well. Same test.

Who is the "they" that replaced the pump? A dealer? Independent Volvo shop?

When the car "died" what did it do? Was it in motion at the time? how fast?

Good Luck,

Bob

:>)