I've had good luck cleaning, unclogging, and testing my '81 242 B21F kjet system by the following:
Add a fuel injection cleaner such as BG 44K or Chevron Techron to the tank then add fuel to mix it up.
Dismount the injectors but leave connected and slip some clear tubing over each. Install a clear plastic bottle (soda bottle works) on each tube.
Remove the large plastic intake air duct at the kjet air meter.
Jumper power to the fuel pump fuse and raise the disk in the kjet airmeter to control the fuel flow.
Observer the injectors' spray in the tubing and then let the system soak as needed. Pattern should be cone shaped with no gaps or separate streams.
You will need the Volvo Wiring Diagrams manual for your year and model, available for download at https://ozvolvo.org/archive.
Also download from the internet, the Bosch K-jetronic Fuel Injection Manual