Truck wont start no fire replaced everything execpt the brain for timing could that be the reason it wont fire

Personally, I think your friend is full of it. ECU replacements are done all the time.

There can be several reasons to check and must start by a flow chart fuel line, fuel supply, firing and then the timing. Check the electricals and see if there is firing, check ur firing sequence.

check the firing order
you could be 180 degrees out

go to the basics; fuel, fire and compression. Is it possible you messed up the timing?

sounds like your ignition timing is off

Did you use all the electrical parts off the old engine? If not your ECM (Brain Box) may not be interfacing with the new parts which most likely require a different ECM . Also, insure all wireing harness connections are tight and that you have a good ignition coil/ power to it as well.

I CHANGE CAM AND CRANK SENSOR,FUEL PUMP,COMPUTER BRAIN BOX AND COIL PACK STILL GETTING NO FIRE UNLESS I JUMP A FIRE WIRE FROM BATTERY

bad ground wire or bad ecm

need a new timing chain and gears

Take the distributor cap have someone crank the car and look if rotor turns, look at rotor conditions, I am sure that you have replaced it, hot wire from positive on the battery to positive on the coil, if car starts after you have a problem on the key, Is it fuel getting to the injectors? after You replaced so many things,if your rotor is not turning when You crank the engine, your timing chain must be defective or timing gear,