The one in the tank i can imagine is simple to dissasemble, but there is one under the car right? How hard is that one?

 

on a regina FI system, there is only the in-tank pump, but AFAIK, 1992 240's are purely Bosch, it was the 740/940s that came both ways.

the under-car pump is a lot easier to replace than the in-tank one. jack up car, put on stands (or a proper lift), drop the pump assembly plate, disconnect pump, install new and replace the filter while you're there (its right next to it), and reinstall, varoom. thre's some rubber mount pieces you might want to replace too, they keep the pump vibration quiet.


here's the parts diagram for a mid production 240 main fuel pump assembly ... your 92 is essentially the same, although some of the PN's might have changed.

 

I assume you have a Regina, in a '90 740 N/A? Then you have ONLY ONE pump in the gas tank... Then see this:

Fuel System: Pumps, Relays

 

so wait, reginas only have ONE pump? its for a 90 740 gl

 

yes, most Reginas only have the in-tank pump, which is a high pressure pump.

read all about it here,
Engine: Fuel Injection

there are (somewhat rare) 2 pump regina cars, and there are 1 pump Bosch cars. Fun?

here's the tank pump replacement procedure.
Volvo Fuel Tank Pump/Sender Replacement

 

There are NO 2 pump Reginas, the only One pump Bosch is the 1995 940.

 

these guys say there were some 2 pump reginas in the 89-92 timeframe
Engine: Fuel Injection

maybe that was just in .EU/.UK ? I could see volvo putting a regina engine in a chassis that had bosch pumps, as both systems use the same fuel pressure and flow rates.

a side note, I've also heard the 95 bosch single pump works quite well as a replacement for single pump regina cars, and is a better and more reliable pump.

this same pump was used in many newer volvo models like 850's.