In view of the graphite ring fracture of the mechanical seal component of the fuel booster pump and the discharge fault of “white smoke” in the oil leakage port of the booster pump of an engine,the troubleshooting,cause analysis and experimental verification were carried out.It is found that the throttle nozzle in the tee pipe coupling is screwed in too deep,which forms an ejection phenomenon.As a result,the lubricating oil supply of booster pump is reduced or even interrupted,which leads to abnormal high temperature of mechanical seal components under high speed and dry friction,resulting in graphite ring fracture due to abnormal radial thermal expansion force of static ring seat.After the failure of the mechanical seal components,the leakage of the mixture oil and gas of the engine lubricating oil system results in the discharge fault of “white smoke”.Aiming at the problem of oil supply,the measure to optimize the position of the throttle nozzle was proposed.Through the flow test,the whole machine test and the verification of a large number of applications,the effectiveness of the measure is proved.