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How do I change fuel injectors in a 1990 Cadillac Seville

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Submitted: 9 years ago.
Category: Car
Expert:  OnlineHelp replied 9 years ago.

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Relieving Fuel System Pressure

  1. Disconnect the negative battery terminal to avoid possible fuel discharge if an accidental attempt is made to start the engine.

  2. Loosen the fuel filler cap to relieve tank vapor pressure.

  3. Attach a fuel gauge (J 34730) or equivalent to the fuel pressure connection. Wrap a shop towel around the fitting while connecting the gauge to avoid spillage.

  4. Install the bleed hose into an approved container and open the valve to bleed the system pressure. Fuel connections are now safe for servicing.

  5. Drain any fuel remaining in the gauge into an approved container.

4.5L Remove and Install Injectors

  1. Disconnect the negative battery cable.

  2. Properly relieve the fuel system pressure.

  3. Raise the hood, install fender covers, and remove the air cleaner assembly.

  4. Remove the fuel rail assembly. With the fuel rail inverted, detach the electrical connector to each injector by pushing in on the connector clip while pulling the connector body away from the injector. Spread open the clip slightly and slide the clip away from the fuel rail. (See Below for Instructions)

  5. Remove the injector by twisting back and forth.

  6. Disassemble the injector O-ring seals from the injector and discard.

To install:

  1. Lubricate the new injector O-ring seals with petroleum based grease and install it on the injector assembly.

  2. Install a new injector clip on the injector assembly.

  3. Install the fuel injector assembly into the fuel rail socket as follows:

    1. Push in to engage the retainer clip with the fuel rail cup.

    2. The electrical connectors should be facing the engine front for injectors 1 through 4. The electrical connectors should be facing the engine rear for injectors 5 through 8.

  4. Attach the electrical connector to the injector assembly.

  5. Install the fuel rail assembly.

  6. Energize the fuel pump and check for leaks.

  7. Perform the Idle Learn procedure.

Injector assembly and retainer-4.5L and 4engines

Injector assembly and retainer-4.5L and 4.9L engines

Installing the injector assembly-4.5L and 4engines

Installing the injector assembly-4.5L


Removal & Installation Fuel Rail

When servicing the fuel rail assembly, precautions must be taken to prevent dirt and other contaminants from entering the fuel passages. It is recommended that fittings are capped and holes plugged during servicing.

  1. Bleed the fuel pressure from the fuel system.

  2. Clean the fuel rail assembly and connections. Use a spray type cleaner. Never immerse the fuel rail or components in a liquid solvent.

  3. Remove the fuel feed and return pipes from the fuel rail.

  4. Remove the vacuum line from the pressure regulator.

  5. Detach the injector electrical connectors.

  6. Remove the fuel rail hold-down bolts.

  7. Pull on the fuel rail with equal force on both sides of the rail to remove it.

The fuel rail assembly and fuel pressure regulator mounting

The fuel rail assembly and fuel pressure regulator mounting

Click to Enlarge
Note the fuel rail identification plate

Note the fuel rail identification plate

Click to Enlarge

To install:

  1. O-rings must be replaced on all components that are replaced.

  2. Lightly oil the injector O-rings with clean motor oil.

  3. Place the rail assembly on the manifold and seat the injectors by hand.

  4. Tighten the fuel rail hold down bolts to 22 ft. lb. (30 Nm)

  5. Install the fuel feed and returns by pushing the pipes onto the fuel rail tubes.

  6. Reattach the fuel injector electrical connectors, and plug in the vacuum line to the pressure regulator.

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