Dear Petiboy,

May this find you well. According to the Volvo Pocket Data Booklet: Cars - 700,850,900 (1991-1996), Turbo-equipped cars have Bosch fuel injection. As a result, you will have an in-tank pre-pump and an external main pump.
The external (main) pump is mounted on a bracket,attached to the underside of the floor pan, under the driver's seat. The fuel filter is right next to it.

If you need to change the main pump, first disconnect the negative battery cable clamp from the batter, and put the clamp into a plastic bag. This ensures that any banging needed to remove the main pump, will not trigger the airbag, the sensor for which is mounted on the floor pan, inside the car, under the driver's seat, above the externally-mounted main fuel pump.

Have you checked the fuel pressure, at the Schrader (bicycle-type) valve, on the underside of the fuel rail. The pressure should read 43 pounds/square in. Also, when was the fuel filter last changed? A clogged filter can degrade performance.

Hope this helps.

Yours faithfully,

spook