My manual shows the fuel injectors have a resistance of 2 ohms. You will not get a resistance to ground at the fuel injector connectors because there is none with the engine off. The green wire at the fuel injectors supplies 12 volts + through the injection relay via fuse #1. The grey wires at the injectors get grounded through the LH-Jetronic Control Unit. There should be 12 volts + at the green injector wire to ground while the engine is cranked, or for a second or two when the ignition is switched on.

If you have fuel spraying out of the injectors when cranking the engine then this is a normal situation as long as when you disconnect the injector wires they stop spraying. It sounds as if your injectors are very dirty if they are spraying like hoses. The leaking injector is no good. You should try to get all of them cleaned and replace the bad ones.

If you remove the injection relay and the engine keeps running there is definitely something wrong with the wiring. Pulling fuse #11 only disables the in-tank fuel pump, not the main pump which uses fuse #1.

Do you have a Volvo fuel injection service manual? It would take you step by step through the troubleshooting process. Let me know if I can be of any help.