  Temperature and doping dependent tunneling spectroscopy on
$Bi_2Sr_2CaCu_2O_{8+\delta}$ single crystals has been investigated by using
break-junction technique. The results provide direct evidence that the
pseudogap persists into heavily overdoped regime, possibly in whole doping
range of the superconducting phase. The gap value determined from the
peak-to-peak of the conductance, $\Delta_{p-p}$, exhibits a jump-like increase
as $T$ is raised across the critical temperature. The magnitude of the jump,
the pseudogap opening temperature and superconducting gap decrease with raising
doping. The $\Delta_{p-p}$ below $T_c$ can be naturally treated as the vector
sum of two competing orders: a BCS-like superconducting gap and a residual
pseudogap.
