<p>The electronically controlled fuel injector for heavy oil common rail systems is a critical component of the fuel injection system in marine diesel engines. The sealing integrity of the fuel injector directly affects fuel injection control accuracy. This study addresses the failure of seals in electronically controlled fuel injectors for heavy oil common rail systems used in marine applications. A numerical model is developed to simulate cavitation phase change and erosive wear of the seals, specifically focusing on the orifice plate ball valve assembly and the needle valve pair. Experimental methods are employed to investigate and validate the effects of clearance flow velocity, pressure, cavitation range, and wear rate on the failed seals. The results indicate that the conical surface of the orifice plate is the primary site of cavitation failure, with the cavitation volume in the orifice plate exceeds that in the nozzle by more than 100&#xa0;t. In contrast, the spherical surface is primarily affected by erosion and wear due to heavy oil impurities, with its wear rate being over 20&#xa0;t greater than that of the conical surface of the needle valve pair. The combined effect of cavitation and erosive wear leads to the sealing failure of the spherical valve component in the orifice plate. Notably, the needle valve pair exhibits minimal cavitation phenomena, and its conical surface is similarly affected only by erosion and wear from heavy oil impurities. This study elucidates the failure patterns and mechanisms of the sealing components in fuel injectors, providing valuable insights and a theoretical foundation for optimizing the design of common rail electronic fuel injection systems in marine applications, as well as for implementing anti-wear measures and controlling cavitation.</p>