How to Replace Fuel Injectors on a 300ZX

Nissan 300ZX

Fuel injection systems have many advantages over earlier carbureted engines. They tend to be more fuel efficient and produce more power. They are computer controlled, so they don't require the constant mechanical adjustment that carburetors do. Over time though, fuel injectors can become clogged or begin to leak. If your Nissan 300ZX is experiencing a loss of power, or you can smell gasoline vapors coming from beneath the hood, your fuel injectors may be the culprits.

Things You'll Need

• Flat blade screwdriver
• Set of metric sockets
• Set of metric wrenches
• Adjustable wrench
• Waste oil collection pan
• Needle nose pliers
• Replacement fuel injectors
• Replacement o-rings
• Shop rags

Instructions

Disassembly

1. Release the pressure in the fuel system, by removing the fuel pump fuse from the fuse block while the engine is operating. Once all the gasoline is drained from the lines, the engine will shut off. Crank the engine over for 5 seconds to make sure all the pressure is released.

2. Disconnect the ground cable from the negative battery terminal.

3. Drain the cooling system by opening the petcock valve on the bottom of the radiator, or disconnect the lower radiator hose.

4. Separate the hoses and wiring from the intake manifold collector. Be sure to label each wire and hose for proper reinstallation.

5. Lift the intake manifold collector out of the engine bay and set it aside.

6. Loosen the bolts and remove the fuel injector retainer. Disconnect the fuel line and remove the fuel rail as a complete unit.

7. Remove the bolts that connect the fuel injectors to the fuel rail, then pull out the fuel injectors.

Reassembly

1. Lubricate each new o-ring with gasoline before sliding it onto the new injector. Then carefully slide each new injector into the fuel rail.

2. Clean any dirt, grease or gasket material from the mounting surface before replacing the fuel rail gasket.

3. Slide the fuel rail into position. Reinstall the fuel injector retainer and reconnect the fuel line.

4. Install the fuel pump fuse into the fuse block to pressurize the fuel system. Check for leaks.

5. Reinstall the intake manifold collector assembly.

6. Follow the labels you made previously and reconnect all the electrical wires and hoses to the intake manifold collector.

7. Refill the radiator using a fresh 50/50 mix of antifreeze and water.

8. Connect the ground cable to the negative battery terminal.

9. Run the engine for at least 5 minutes to ensure proper fuel system operation. Check for leaks or gasoline vapor fumes.

10. Allow the engine to cool, then check the fluid level in the radiator.

Tips & Warnings

• If you can't find the fuel pump fuse, you can disconnect the harness connector at the gas tank to relieve the fuel system pressure. The "Check Engine Light" may come on after you have completed this repair. To reset the system, simply disconnect the negative battery cable and wait 1 minute before reconnecting it.

• Gasoline is highly flammable and its vapors are highly toxic. Always work in a well ventilated area. Be aware of any sources of heat or spark such as power tools, shop lights or portable heaters. Antifreeze is highly toxic if ingested. Keep it away from small children and pets. Always follow local regulations with regards to the disposal of antifreeze.

References

• "Chilton's Import Car Manual 1992-1996"; Chilton Book Company; 1995

Resources

• Nissan 300ZX Club