in the protank, if it tastes metallic it can be that the coil is not touching the wick at all times.. or you have one of your coils touching the side of the base.. if it tastes burnt rubber..you might have burnt one of your insulators.
when you first test your coil to make it glow, don't go full power.. start at low volts
when you first test your coil to make it glow, don't go full power.. start at low volts