No start issue

Hi guys, I swapped a K20a2 into my EP3 and after connecting everything, the car cranks but refuses to start.

I checked the main 80A and the 50A relays under the hood and they were both fine.

I checked the ignition coils and they were putting out a spark, plus I can hear the fuel pump priming. Also there is compression.

I have also tested the fuel injectors and they clicked when I plugged them into a 12V battery.

I connected a volt meter to the positive and negative side of the fuel injector connector and I'm not getting anything. I am only getting power if I connected the negative lead to ground. I also tried this with a LED light and it lights up if I connect to the positive side and ground, not positive to negative.

I am almost out of ideas, can anyone shed some light on this? If you did this swap, did you have the same problem?

ps, not sure if it's the issue but I used the crankshaft and camshaft sensor from the old block. I also checked the connectors and sure enough they were getting power.

Any help is appreciated, thanks.