Internal fuel pump filter is 22602-56350. More experienced people than me will be able to post how to remove and clean it. The practice with filtering is that every part of the system is protected so if there is a particle in any part it will be caught. Even during construction in the factory a new main filter-pump pipe may have a particle so this is caught by the pump filter. In use obviously by the time the fuel reaches the pump most of the particles should be caught so the pump filter is very small. The injectors have internal filters as well, so I am told, to protect any swarf coming off the injector pipes and nut threads The main filter is not just tea strainer design. It has extending fibres like seaweed which particles cling to so if your filter is not actually blocked it may still not be doing it's job.