The Sulzer fuel delivery pump has leaing problem with the non-drive end. These pump are critital equipments with the important fuel delivery project in West China. We found the leaking reason is because the special structure of the housing when dismantle the pump. A flange with the housing bore offer limited oil return space. This cuase the difficulty of returning of the oil flashed to the traditional Bearing Isolators. We redesigned the structure the Isolator and choose down oil return hole and enlong the stator to over-ride the flange. This modification has resolve the oil return problem, plus the special structure enhancing the oil return capability, the renovacation is quite sucessful. No any lealing signs has been found since the restart of the pump 2 weeks ago.