19231-ZW1-003 Impeller Cover - Overview. The 19231-ZW1-003 Impeller Cover is a crucial component within Honda marine engine systems, specifically designed for the water pump assembly in select Honda outboard motors such as the BF75A and BF90A models. This impeller cover serves the important role of housing and protecting the impeller, which is critical for maintaining proper water flow and cooling of the engine. By ensuring a snug fit and alignment with other water pump parts, the 19231-ZW1-003