adjust the velocity. idk much about KP's but if they're anything like cockers it sounds like there's too much pressure on the valve. Not broken though just needs to be adjusted.
Okay... adjusted the reg...now it won't fire...
BTW No air coming out of barrel or anything now.. just won't fire.
okay that is because you lowered it too much so that the reg is closed off. try raising it little by little. also try adjusting the velocity as dominerva said
Oh! okay.. sorry.