Converts fumarylacetoacetate to acetoacetate and fumarate (PubMed:22980205). Involved in tyrosine catabolic pathway. Catalyzes the final step in the tyrosine degradation pathway (PubMed:22980205, PubMed:23743712, PubMed:27097641). 4-fumarylacetoacetate + H2O = acetoacetate + fumarate + H(+) Amino-acid degradation; L-phenylalanine degradation; acetoacetate and fumarate from L-phenylalanine: step 6/6. Spontaneous cell death phenotype under short-day conditions. Belongs to the FAH family.