Mercury 4L8Z-9F593-AA Injector Assembly

You can Select Your Vehicle to check if 4L8Z-9F593-AA fits your vehicle.

Relieve the system fuel pressure and disconnect the cable from the negative battery terminal. Remove the strut tower cross brace mounting nuts and brace, if equipped, followed by the upper intake manifold. Disconnect the fuel supply line spring-lock coupling from the fuel rail, then remove the fuel rail insulators. Disconnect the electrical connectors from all six fuel injectors, remove the four fuel rail bolts, and take out the fuel rail and injectors as a single assembly. Release the fuel injector retaining clip and remove each injector from its bore in the fuel rail, discarding the upper and lower injector O-rings. It's advisable to replace all O-rings at the same time, even if only one injector is being replaced. Coat the new upper and lower O-rings with clean engine oil and install them on the injectors, then insert each injector into its bore in the fuel rail and secure them with the retaining clips. For the 4.0L V6 engine, disconnect the fuel supply line spring-lock coupling, remove the mounting bracket bolts, and detach the fuel rail supply tube. Remove the fuel rail flange O-rings and disconnect the vacuum hose and electrical connector from the Fuel Rail Pressure and Temperature sensor. Remove the injector wiring harness and the fuel rail and injectors as a single assembly, pulling each injector out firmly. Replace the old O-rings with new ones and ensure proper installation of the new O-rings on the fuel injectors and at the mounting flanges. For V8 engines, disconnect the fuel supply line spring-lock coupling, detach the wiring harness retainer clips, and disconnect the electrical connectors from all eight fuel injectors. Remove the fuel rail mounting bolts and take out the fuel rail and injectors as a single assembly. Remove the injector retainer clips and the old O-rings from each injector, replacing them with new ones. Coat the O-rings with clean engine oil before installing the injectors back into the fuel rail and securing them with the retainer clips. Finally, install the fuel rail and injector assembly, ensuring that the installation is otherwise the reverse of removal.

To replace fuel injectors, relieve the fuel system pressure, and remove the fuel filler cap. Disconnect the negative battery terminal and remove the air intake duct. Next, disconnect the fuel supply line from the fuel rail and the vacuum line from the fuel pulsation damper. Replace the old O-rings on each injector.

To disconnect the fuel injectors from the fuel rail, you need to do the following: a) Disconnect the fuel supply line from the fuel rail. b) Disconnect the vacuum line from the fuel pulsation damper. c) Disconnect the electrical connectors from the fuel injectors.