I have a 2008 6.4L and lately when I go out to do a cold start on the truck I hear a clicking sound on the driver side before I crank the truck up. It sounds like the fuel pump maybe? I don't know where it's at on these trucks. When I first got the truck you could hear it but it sounded normal like all the other 6.4Ls I've heard. But this last week it's gotten louder.

It doesn't matter if I plug the truck up or not.