The transition toward hydrogen-powered transportation requires fueling systems capable of sustaining high-availability operation under demanding cryogenic and high-pressure conditions. Nevertheless, the extreme operating environment within liquid hydrogen fueling hardware introduces failure behavior that is not always straightforward to diagnose. Maintenance issues are typically reported as high-level symptoms such as abnormal high vapor return, failure to operate, or external hydrogen leakage, but these observable outcomes do not directly reveal the internal subsystem degradations responsible for the behavior. This paper presents a structured failure mode taxonomy and a hierarchical failure-chain framework for the cold end of reciprocating liquid hydrogen pumps used in refueling applications. The framework categorizes observable failure modes from contributing subsystem-level failure modes and organizes their relationships within clearly defined system boundaries. By formalizing these linkages, the framework supports more consistent failure classification, improved diagnostic reasoning, and clearer alignment between operational reporting and reliability engineering analysis. This structured approach provides a foundation for future failure mechanism focused studies and reliability improvement efforts in cryogenic hydrogen pump systems.