starts, won't run
 

i'm doing ls1 swap from a 04 gto into 96 240sx. the engine fires right up and then dies.:confused: any suggestions what would cause this

Check to make sure that you have the keyed 12V hooked to a wire that is a true keyued 12V - not one that only has voltage when in the crank position.

The number one answer to this question is usually is "VATS", is it wired up with the BCM and Key, is it disabled or do you have a VATS Bypass/simulator?

other would be to check the battery 12v's as GenIIIDude suggested, also check the grounds, fuel pressure and voltage to the relay.

i checked voltage and it was good. when i turn the key on the fuel pump turns on for few second's and shuts off like normal. there is fuel pressure at the fuel rail scrhader valve. vats should be removed but i can't confirm that it was.

Sounds exactly like a VATS problem. Ill bet it wasnt disabled.

werd to VATS