Crank No Start

After a engine swap, from a 01 1.9L to a 03 1.9L, the engine started right up. After four good starts, I got a error code, P0036. Erased code, yet I forgot to turn the key off. Sat this way for 3 days. Came back and tried to start, thinking dead battery, I tried to jump start the car. No luck, Than I noticed the car with a X on the dash was flashing, (the Immobilizer light). Pulled the code came up with a P0600. Sent the IMMO and ECU out to be checked, The company that did the work for me made me a new key, reinstalled the IMMO, ECU and using the new key, I was now able to get the car to crank, where as before It would not even turn over. After many, many hours of troubleshooting, this is what I have come up with, relays good, fuses good, I have fire to the plugs, good fuel pressure at the rail, power to the injectors, Once I try to start the, the injectors will spray for just a short second, than stop. Pulled the plugs and they are not wet with fuel. Have not checked the ground/puls side(ECU) for the injectors, If every thing else is working in the ignition system what could cause the injectors not to fire?