I am doing an engine swap on a 1997 F-150 with a 4.6,swapping with a 1999 5.4. Have engine,tranny and engine harrness PCM installed that part was easy,but engine will not start,fuel is at the rails,if i pour some fuel into the throttle body it will run,What the heck.Any one have any idea what to do.

 

Check to see if the fuel injectors are getting a signal from the computer to fire. If the 99 engine has not been used for a while, it is possible to have clogged injectors as well. Also, make sure that there is enough fuel pressure at the rail, it won't run without enough pressure.

 

I had the same issue, put the 97 pcm in and it should crank if all is ok. It is the pats security in the 99 will have to have it reflashed and you may have other problems like me.