Freelander 1.8 facelift Injector issue Low Voltage

Hey All, so i have the following issue, from left to right (as you are looking at the engine from the front of car) injector 4 does not work.

What i did: i also have GPL instalation on it, on GPL it runs ok 4outof4 cylinders. I went ahead and disassembled the intake took out the injectors, gave them current from a battery, improvised an adapter on their fuel intake head and started the cleaning process, mounted back, injector 4 does not spray when trying to start, put the injector 3 plug to injector 4, and injector 4 works, than went to measure the voltage on the each injector jack and all give around 8v and the 4th one gives 5v, might not be accurate i measured with ignition on and not when crancking. In conclusion there is some current coming to injector 4 but what should the issue be?
Conclusion: If it was the wiring will it either give a short or no current at all? Or could it be or does it have an injector ECU? That might have the issue.?

All advice are welcomed. And thank you!

The injectors are powered by 12 Volts from one of the engine bay fuses. The ECM pulls the injectors to ground to trigger them.
I'd be checking the wiring for breaks and damage.

So i found the issue it was the GPL instalation, the ECU from the GPL was wired directly to the cars ECM and did some funny stuff and shorted a couple of wires, had to make a bypass on 2 leads and worked. Thank you for the help!