A few weeks ago, I changed the plugs on my 07 F150 5.4 at about 120K miles. The plug change went surprisingly well, with the exception of one of the eight new plugs being defective. The bad one was in the #7 cylinder so I threw one of the used ones back in and the truck ran great. Yesterday, I finally got around to changing that one remaining plug, reinstalled the COP and plugged the two harnesses back in for the COPs and the other harness that I had unplugged to access the plug. Now the truck won't start. Turns over fine, but won't fire at all. It is not throwing any codes at all. Anybody have any idea what I may be dealing with?

 

Don't know how or why, but the 20A fuse for the fuel pump was blown...Replaced fuse, runs again.

 

Love It when its an EASY fix!

 

Thanks for reporting back on the fix.