V6 to V8 Swap: Wont Start

[Dirty 30]

My truck was a 2003 Reg Cab Silverado with manual accessories and 4.3L V6. I did a complete swap to all power accessories and 5.3L V8 including all the fuse boxes, PCM + BCM, interior and engine wiring off 2003 Reg Cab also.

Everything is connected right and nothing seems damaged. The first try, I turned the key and the security light came on. I did the relearn thing and the security light went away on the 3rd try but on the 4th try it still didn't start. I tried the relearn thing 3 differnt times.

The crank turns over and you can hear the fuel pump working. I removed the #1 spark plug wire and stuck a spark plug in it to see if there was spark, but no spark.

I need help please.

[horsepwraddict]

is it getting fuel? put a diode on the injectors and see if they are pulsing when you crank.

As far as spark goes, start tracing backwards, make sure its not just that cylinder not getting spark, Thats a coil near plug system (one coil per plug) isnt it? Check for power to the coils, if you have power it has to be a problem with a triggering device like the ignition module. Check the module and see if it is sending a signal (an ocsilliscope is what you'll need). If its not the module, start checking sensors, i think on these motors the crank sensor is near the back, but dont hold me to it, make sure its sending a signal. Also check the cam sensor, that is usually what controls the injectors.

Dont use a test light on computer circuits, use a scope or a good volt meter, you can burn up computers using test lights. Test sensors with a scope or volt meter, either will work. You can use a volt meter but it may fool you, just because it reads no voltage doesn't mean the sensor is dead, it could be a pull up circuit which in case it wont send a voltage signal untill the switch is activated so bump the engine over several times and see if it changes.

i know it sounds complicated, it can be and it isn't fun but its gotta be done.