GM 12559036 Multiport Fuel Injector Assembly

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To remove the fuel rail and injectors, start by relieving the fuel system pressure and disconnecting the battery. Then, remove the intake manifold service cover and the air intake duct. On 1999 models, also remove the throttle body and gasket, as well as the throttle body spacer and spacer gasket. Disconnect the fuel supply and return lines from the fuel rail, and on 2005 and earlier models, disconnect the vacuum hose from the fuel pressure regulator. On 2000 and later models, disconnect the PCV fresh air tube. Remove the nut attaching the fuel rail end-point bracket retainer, and disconnect the electrical connectors from the fuel injectors. Remove the nuts securing the coolant pipes to the front fuel rail mounting studs, and then remove the fuel rail and injectors as a single assembly. To remove an injector from the fuel rail, flip up the U-clip retainer and pull out the injector. Finally, remove the old o-rings from the injectors. When installing the injectors, use new o-rings and, on 1999 models, a new gasket for the spacer. Tighten the spacer bolts to the specified torque. Installation is the reverse of removal, and be sure to check for fuel leaks after starting the engine.