Abstract: A fuel injector assembly is adapted to inject a compressed fuel into a combustion chamber of an internal combustion engine. The compressed fuel is stored in a fuel storage tank at a fuel storage pressure and delivered to the fuel injector assembly through a fuel supply line at a fuel supply pressure. The fuel supply pressure is lower than the fuel storage pressure. The fuel injector assembly includes a fuel injector and an adapter valve. The fuel injector injects the compressed gas fuel. The adapter valve is positioned between the fuel injector and the combustion chamber. The adapter valve allows the compressed gas fuel injected by the fuel injector to be discharged from an outlet of the adapter valve into the combustion chamber in an injection direction while preventing blowback gas entering the outlet from passing through the adapter valve in an ingress direction opposite the injection direction.