Outer Limits 4x4 Board

Hi, been looking through the site for info, cant find any, I have a sierra with a G13b fitted, I drove it to work one day, jumped in it at the end of the day and it wouldn't start. Im not a mechanic but the engine has spark, fuel to the fuel rail and cranks over. I bought some test nodes to check if the injectors were getting any signal and they are not. It has a EM2 computer fitted. I have fitted new plugs, leads and coil whilst trouble shooting, it is probably something simple any ideas would be great.
Thanks for you help.

injectors work off a negitive trigger, is there 12v to one side of the injector on all injectors?
check the injector harness plug for corrosion or not connected properly??
same at the computer end