The injector with good performance should have obvious and clear cracking sound when spraying oil, the atomization quality should meet the requirements, no later dripping oil phenomenon, otherwise the injector should be cleaned again or replaced.Press the handle of the fuel injector tester to control the oil pressure at 0.98~ 1.98mpa. There should be no leakage around the nozzle hole and the fastening nut within 10s (see figure 4), otherwise it should be reassembled and adjusted. Do not meet the requirements, should be replaced with a new couple.