I have a 2000 dodge ram 1500 5.2 My #4 fuel injector has 13.5 volts going to the injector when I test the leads going to the injector when it is running. The rest of them only have 1.5 to 1.7 volts. what is the problem. Pack rats ate the coating off the wires and they shorted out. I replaced the #4 injector with no luck

 

so somewhere back in the wiring harness, around the rat snack area, a 12-14 volt battery hot wire is shorted to the #4 injector wire. can you cut the harness apart and expose the injector lead.

welcome to df.
damn a rat.