GMC 12599504 Multiport Fuel Injector

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Do not swap fuel injectors between different applications because they have different flow rates. Relief of the fuel system pressure is necessary to start the removal process as well as disconnecting the cable from the negative battery terminal. Remove intake manifold for inline engines and clean the fuel rail/fuel injector area. Take off the fuel pressure regulator vacuum line, fuel injector harness connector, and fuel line fitting(s). VS engines involve removing the outlet duct from air filter housing and labeling and disconnecting all interfering engine hoses, wiring harnesses, and electrical components. The purge control solenoid valve should be removed and quick-connect fuel filling disconnected from the fuel rail. Unbolt the fuel rail attaching bolts for all engines and apply some gentle even outward pressure on it towards cylinder head to free it. Disconnect electrical connector(s) from injector(s) being removed then remove retaining clip(s) and injector(s) from the fuel rail assembly. Replace O-rings of injectors, lubricate with clean engine oil then press injectors into the fuel rail until they are seated. Finally, install injector retaining clips, inspect and clean cylinder head injector holes if required. The remaining part of installation is reverse of removal only taking care that one has tightened down on the bolts mounting a fuel rail properly. After installation turn your ignition switch to ON without operating starter to activate the pump. Turn ignition ON/OFF several times checking for any leakage in fuel lines, fuel rail or injectors.

Replace the injector o-rings, lubricate them with clean engine oil, and press the injector into the fuel rail until it is seated.

Remove the intake manifold and clean the fuel rail/fuel injector area. - Disconnect the fuel pressure regulator vacuum line, fuel injector harness connector, and fuel line fitting(s).