GMC 12594512 Sequential Multiport Fuel Injector Assembly

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To remove the upper intake manifold, first disconnect the negative battery cable and relieve fuel system pressure. Disconnect various electrical connectors, including those for the EVAP canister purge solenoid and MAP sensor, and remove the PCV crankcase ventilation hose. Remove the upper intake manifold mounting bolts and throttle body mounting studs, and discard the old gasket. To remove the fuel pulsation damper, remove the retaining clip and pull it out of the Throttle Body, then discard the old o-ring. To remove the throttle body and injectors, remove the fuel supply line and various seals, detach the injector poppet nozzles, and remove the injector retainer nuts and retainer. Installation for all components is the reverse of removal, using new gaskets and o-rings where necessary and tightening fasteners to proper torque specifications.

First, remove the intake manifold cover to get it off the fuel injectors on a vehicle. It is also necessary to relieve the fuel system pressure and disconnect the negative battery terminal cable. After that, air intake and manifold cover bracket bolts are removed as well as the nut holding engine wiring harness bracket to intake manifold. Electrical leads in engine wiring harness traced and disconnected from various components including alternator, EVAP purge solenoid, ignition coils, MAP sensor and throttle body. Also, electrical connectors from fuel injectors were disconnected; engine wiring harness clips were detached too. The PCV hose is disconnected from the intake manifold while the fuel line is disconnected from the fuel rail. The EVAP canister purge solenoid is removed from the intake manifold while the fuel rail mounting bolts are removed. Thereafter, injectors are disengaged from engine as an assembly through lifting them out of top of intake manifold by each individual injector retainer with its old o-ring removed.New o-rings should be installed after which they are lubricated with clean engine oil before reassembling both injectors and fuel rail. This process however must be done in reverse starting by tightening up of fuel rail mounting bolts and then pressurizing of fuel system so as to ensure there are no leaks occurring during installation.

The PCV hose needs to be disconnected from the intake manifold, and the fuel line needs to be disconnected from the fuel rail.

The new O-rings should be coated with engine oil.

During the installation process, the fuel rail mounting bolts need to be tightened securely and the fuel system needs to be pressurized to check for leaks.

Before reassembling the injectors and fuel rail, each injector retainer and old o-ring needs to be removed. New o-rings should be installed and lubricated with clean engine oil.

Use new gaskets and o-rings where necessary and tighten fasteners to proper torque specifications.

Remove the PCV crankcase ventilation hose.

The air intake and manifold cover bracket bolts need to be removed, along with the nut securing the engine wiring harness bracket to the intake manifold.

Disconnect various electrical connectors, including those for the EVAP canister purge solenoid and MAP sensor.

Disconnect various electrical connectors, including those for the EVAP canister purge solenoid and MAP sensor.