My buddy changed out his injection pump on his 1991 ford f350 7.3l idI non turbo, he got a rebuilt one frim rock auto, it was a stanadyne 4812 pump this rruck calls for a 4821?and it was poring out black smoke and no horse power, after taking care of the fuel leaks and timing it it ran better but still slight black smoke under load, ordered a set of rebuilt injectors from diesel logic , put them in now the truck blows a light white smoke and rough idle and a knocking sound if you bring up the rpms. Could one or more rebuilt injectors be bad ? Oh and the original injectors are stamped with a D and the rebuilt are stamped with BB ?