REMOVAL & INSTALLATION
See Figures 1 through 12
- Remove the upper intake manifold (except 4.6L SOHC engine). Be sure to depressurize the fuel system before disconnecting any fuel lines.
- Disconnect the fuel supply and return line retaining clips.
- Detach the vacuum line from the fuel pressure regulator.
- Disconnect the fuel chassis inlet and outlet fuel hoses from the fuel supply manifold.
- Remove the four fuel supply manifold retaining bolts.
- Carefully disengage the fuel rail assembly from the fuel injectors by lifting and gently rocking the rail.
- Remove the fuel injectors from the intake manifold by lifting while gently rocking them from side to side
- Place all removed components on a clean surface to prevent contamination by dirt or grease.
Never use silicone grease; it will clog the injector. All injectors and the fuel rail must be handled with extreme care to prevent damage to sealing areas and sensitive fuel metering orifices.
- Examine the injector O-rings for deterioration or damage; replace them as needed.
- Make sure the injector caps are clean and free from contamination or damage.
- Lubricate all O-rings with clean engine oil, then install the injectors into the fuel rail using a light twisting/pushing motion.
- Carefully install the fuel rail assembly and injectors into the lower intake manifold. Make certain to correctly position the insulators. Push down on the fuel rail to make sure the O-rings are seated.
- Hold the fuel rail assembly in place and install the retaining bolts finger-tight. Then, tighten the bolts to 15-22 ft. lbs. (20-30 Nm) for the 3.8L and 5.0L engines, or to 71-106 inch lbs. (8-12 Nm) for the 4.6L SOHC and DOHC engines.
- Connect the fuel supply and return lines.
- Attach the vacuum hose to the fuel pressure regulator.
- Connect the fuel injector wiring harness at the injectors.
- Connect the vacuum line to the fuel pressure regulator, if removed.
- Install the air intake and throttle body assembly.
- Run the engine and check for fuel leaks.
FUEL INJECTOR TESTING
See Figures 12 through 18
If you want to test the fuel injectors because of a fuel system problem, it is a good idea to test the entire system; refer to the fuel system test charts earlier in this section.
The fuel injectors can be tested, however, with a Digital Volt-Ohmmeter (DVOM). To test an injector, detach the engine wiring harness connector from it. This may require removing the upper intake manifold or other engine components.
Once access to the injector is gained and the wiring is disconnected from it, set the DVOM to measure resistance (ohms). Measure the resistance of the injector by probing one terminal with the positive DVOM lead and the other injector terminal with the negative lead. The resistance measured should be 11-18 ohms. If the resistance is not within this range, the fuel injector is faulty and must be replaced with a new one.