GMC 12651989 Rail Assembly, Fuel Injection Fuel

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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 retaining clip should be removed and the O-rings and seals should be replaced.

The electrical leads from various components, including the alternator, EVAP purge solenoid, ignition coils, MAP sensor, and throttle body, need to be traced and disconnected.