Hi I have a 2004 Dodge ram 1500 I Just replace the engine in it and now it wont start but what is funny is i drove it in my garage after putting new engine in it wont start I Have good fuel pressure i have checked all the fuses reset the computer and i still getting codes i have replace the cam and crank senors should there be power at the coils when i turn the key or does it only last a few secs reason im asking is i only have power to my coils for a sec or two when i turn the key then i lose it can anyone help i have been trying to figure this out for weeks now.

 

I'm having the same problem. I have weak spark and the voltage to my crank cam and tips read 4.75. The tps reads 4.0 volts. Try to start it blows out the throttle body like a back fire

 

Check the condition of the TIPM. They can cause issues if corroded underneath.

I would also check all of the chassis grounds.