I am wondering if the OP can exchange them for a different set of BKP free of charge?
Theoretically, yes - depending of course on where and when he bought them. But given the symptom I don't think this would change much, as there's obviously a problem with either the electronics or (shite happens) the pups themselves.
@OP: just what AndrewW said - solder one of the pups directly to the output jack and you'll know whether the problem comes from the pups or else. I understand Apaches may have a fatter / more rounded tone than 60s style pups but what you describe is definitly NOT how they should sound.
Oh and yes : sorry for stating the obvious, but if you didn't yet, make sure the problem is not between the guitar and amp (faulty cable / pedal / whatever) nor with the amp itself. May sounds ridiculous but it did happen to me once :-/