First, you may have gotten a bad injector.
Since the injector is new, dirt shouldn't be an issue. Therefore, start by checking the fuel injector 3 harness for an open or shorted wire or connection as well as the number 3 circuit poor electrical connection due to corrosion.
NOTE: I assume that the number 3 injector is the one you replaced.
Friday, August 28th, 2015 AT 9:01 PM