Repair And Fix it

General Motors has manufactured a series of diesel engines under the Duramax brand since 2001. The primary application for these eight-cylinder, 6.6-liter engines is in heavy trucks requiring low-end torque, like full-size Chevrolet pickups and vans. A Duramax diesel engine uses fuel injectors to send fuel to the cylinders under high pressure. The replacement of the fuel injectors is a relatively simple process, but it also requires the removal of various components to access the injectors.

Instructions

1

Disconnect the negative battery cable with a socket wrench and drain the coolant from the radiator into a suitable container. Detach the electrical connector for the air cooler from the left side of the turbocharger. Unplug the barometric sensors electrical connector.

2

Disconnect the clip for the wiring harness on the engine, and remove the wiring harness bracket with a socket wrench. Unplug the electrical connector for the glow plug. Disconnect the positive crankcase ventilation hose from the left side of the crankcase.

3

Use a socket wrench to disconnect the air cleaner outlet duct from the right side of the engine. Loosen the clamps on the hose to the air intake on the right side of the engine and remove the hose. Disconnect the fuel filter and fuel filter bracket from the right side of the engine. Disconnect the fuel injector control module.

4

Blow compressed air on the fuel lines for the fuel injector. Clean the fuel lines with a shop rag.

5

Detach the fuel send and return lines from the fuel injectors. Unplug the electrical connector from the fuel injector. Disconnect the bolts on the fuel injector bracket, and install injector removal tool J-46594 into one of the bolt holes. Attach a flare nut wrench to the other end of the injector removal tool and pull the flare nut wrench to unseat the fuel injector.

6

Lift the fuel injector from its bore. Discard the O-rings and copper washer for the fuel injector.

7

Mount a new copper washer and O-rings to the new fuel injector. Install the fuel injector, and tighten the bolts on the fuel injector bracket to 22 foot-pounds with a torque wrench. Attach the electrical connector and fuel lines to the fuel injectors. Torque the mounting bolts for the fuel lines to 30 foot-pounds.

8

Complete the installation of the fuel injectors by performing steps 1 through 3 in reverse order. Refill the coolant in the radiator. Start the engine and check for any fluid leaks.

The Mustang is a series of cars manufactured by the Ford Motor Company since 1964. The 1994 models were the first fourth generation Mustangs and represented a major redesign from the previous generation. The standard for the 1994 and 1995 Mustangs was a 6-cylinder 3.8-liter engine with electronic fuel injection. The fuel injector in these vehicles is located on top of the engine and is part of the fuel supply manifold assembly.

Instructions

1

Open the fuel tank cap to relieve the pressure in the fuel tank. Connect fuel pressure gauge T80L-9974-B to the pressure relief valve on the fuel supply manifold. Place the open end of the hose for the fuel pressure gauge into a container approved for gasoline. Open the pressure gauge to relieve the pressure in the fuel system and disconnect the pressure gauge from the relief valve.

2

Release the retaining clips for the fuel lines on the fuel supply manifold and remove the vacuum line on the fuel pressure regulator. Detach the fuel lines from the fuel supply manifold and disconnect the retaining bolts on the fuel supply manifold with a socket wrench.

3

Rock the fuel rail assembly back and forth gently to detach it from the fuel injectors. Use the same technique to disconnect the fuel injectors from the intake manifold. Replace any damaged O-rings for the fuel injectors.

4

Apply a thin layer of engine oil to the O-rings and install them on to the fuel injectors. Connect the fuel injectors to the fuel rail by gently pushing and twisting the fuel injectors. Install the fuel rail assembly onto the fuel supply manifold and ensure the O-rings are properly seated.

5

Tighten the mounting bolts for the fuel supply manifold with a torque wrench. These mounting bolts require a torque of 15 to 22 foot-pounds for the 3.8-liter and 5.0-liter engines and 71 to 106 inch-pounds for the 4.6-liter engines. Connect the fuel lines to the fuel supply manifold and connect the vacuum line to the fuel pressure regulator. Attach the retaining clips for the fuel lines on the fuel supply manifold.

6

Turn the ignition on for a few seconds to pressurize the fuel system and start the engine. Check and correct any fuel leaks.

The Nissan Maxima is a mid-size car manufactured by Nissan since 1976. The third generation of this vehicle was in production from 1989 to 1994 and represented a major redesign. All versions of the 1994 Nissan Maxima have a 6-cylinder 3.0-liter engine with sequential fuel injection. The fuel injectors are on top of the engine and their replacement also requires you to remove the fuel rails.

Instructions

1

Disconnect the negative battery cable with a socket wrench to prevent the battery from producing sparks. Remove the collector for the intake manifold. Detach the hoses on the fuel pressure regulator and fuel rails.

2

Detach the electrical connectors for the fuel injector and disconnect the mounting bolts for the fuel rail with a socket wrench. Lift the fuel rail assembly from the engine.

3

Remove the retainer screws for the fuel injector with a socket wrench and press the fuel injector from the fuel rail. Discard the O-rings for the fuel injector and apply a thin layer of engine oil to the new O-rings.

4

Install the O-rings to the new fuel injector and press the fuel injector into the fuel rail. Fasten the retainer screws for the fuel injector with a socket wrench.

5

Place the fuel rail assembly onto the engine. Torque the fuel rail mounting bolts to between 6.9 and 8.0 ft. lbs. with a socket wrench, then torque them to between 15 and 20 ft.lbs.

6

Attach the fuel lines to the fuel rail assembly and connect the hoses to the fuel pressure regulator. Connect the electrical connector for the fuel injectors and install the collector for the intake manifold with a socket wrench. Connect the cable to the negative battery terminal. Start the engine and check for fuel leaks.

The Quad 4 series of engines by General Motors had four cylinders with four valves per cylinder. They were in production from 1987 to 2002, and appeared in various GM vehicles from this period. The 2.4-liter version of the Quad 4 engine was an option on the Chevrolet Cavalier from 1996 to 2002. The procedure for replacing the fuel injectors is generally the same for all Quad 4 vehicles.

Instructions

1

Open the filler cap on the fuel tank to relieve the pressure in the fuel tank, and disconnect the electrical connector from the fuel pump. Start the engine, and allow it to idle until it stalls.

2

Crank the engine for three seconds at a time until the engine fails to start. This ensures that the fuel system is completely empty. Remove the negative battery cable with a socket wrench. Attach the electrical connector for the fuel pump, and fasten the filler cap to the fuel tank.

3

Disconnect the resonator for the air cleaner with a socket wrench, and detach the fuel lines from the fuel injectors. Disconnect the electrical connectors for the camshaft position sensor and the fuel injectors. Detach the vacuum line from the fuel pressure regulator.

4

Disconnect the mounting bolts for the fuel rail with a socket wrench, and remove the fuel rail from the intake manifold. Twist the fuel pressure regulator back and forth to detach it from the fuel rail, and discard the O-ring on the fuel pressure regulator. Release the retaining clips from the fuel injectors, and remove the fuel injectors from the fuel rail.

5

Coat the new O-rings for the fuel injectors with engine oil, and mount them to the new fuel injectors. Install the new fuel injectors to the fuel rail, and attach the retaining clips to the fuel injectors. Connect the fuel rail to the intake manifold, and tighten its mounting bolts to 18 foot-pounds with a torque wrench.

6

Mount a new O-ring to the fuel pressure regulator, and install the regulator to the fuel rail. Tighten the mounting bolts for the fuel pressure regulator to 53 inch-pounds with a torque wrench.

7

Attach the fuel lines to the fuel injector, and plug the electrical connector into the fuel injector. Connect the vacuum hose to the fuel pressure regulator, and attach the electrical connector for the camshaft position sensor. Install the resonator for the air cleaner with a socket wrench.

8

Connect the cable for the negative battery terminal with a socket wrench. Turn the ignition switch on for two seconds, then turn the ignition off for ten seconds to pressurize the fuel system. Check the vehicle for fuel leaks.

No Scheduled Maintenance

Landrover doesnt list a specific recommendation on how often fuel injectors must be replaced as a regular preventive maintenance project. Depending on the fuel quality, the working environment and the type of use to which the vehicle is subjected, the injectors may last the life of the vehicle or need replacing after only 20,000 or 30,000 miles.

Replace With Tune-Up

Modern vehicles dont need engine tune-ups as frequently as vehicles did 15 years ago or more. Regardless of how well a vehicle seems to be running, experts advise a tune-up every 100,000 miles, including changing the motors fuel injectors.

Bottom Line

For peak performance, change the fuel injectors every 100,000 miles. If performance, mileage, hard starting or other performance problems occur, change the injectors more frequently.