The injectors deliver a measured quantity of fuel according to signals from the ECM. As driving conditions change, the computer signals each injector to stay open a longer or shorter period of time. The injector, being an electric component, is either on or off (open or closed); there is no variable control for an injector other than duration.
Cleanliness is important when working on a fuel injected system. Every component must be treated with the greatest care and be protected from dust, grime and impact damage. The injectors are easily damaged by improper handling. Additionally, care must be used in dealing with electrical connectors. Look for and release any locking mechanisms on the connector before separating it from the injector. When reattaching, make sure each pin is properly lined up and seated before pushing the connector closed.
REMOVAL & INSTALLATION
See Figures 1 through 5
- Disconnect the negative battery cable.
- Unplug the injector electrical connections. Be sure to release the locking tabs before attempting to unplug the connector.
- Remove the fuel rail assembly.
- Pull the injectors free of the delivery pipe. Certain engines may use injectors with color-coded collars. Note these positions for correct placement during installation.
Always use new O-rings and gaskets when installing fuel system components.
- Install a new grommet and O-ring on each injector. Apply a thin coat of gasoline to the O-ring (NEVER use oil of any sort), then install the injectors into the fuel rail. Make certain each injector can be smoothly rotated. If they do not rotate smoothly, the O-ring is not seated correctly and should be replaced. On injectors with color-coded collars, be sure they are installed in the proper order.
- Install the fuel rail assembly.
- Once again, check that the injectors rotate smoothly.
- Engage the electrical connectors to each injector. On color-coded injectors, engage the gray connectors to the dark blue injectors, then the brown connectors to the brown injectors.
- Connect the battery cable to the negative battery terminal. Start the engine and check for leaks.
See Figures 6 and 7
The simplest way to test the injectors is to listen to them with the engine running. Use a stethoscope-type tool to touch each injector while the engine is idling. You should hear a distinct clicking as each injector opens and closes.
Additionally, the resistance of the injector can be easily checked. Disconnect the negative battery cable and unplug the electrical connector from the injector to be tested. Use an ohmmeter to check the resistance across the terminals of the injector. Correct resistance is approximately 13.8- at 68°F (20°C); slight variations are acceptable due to temperature conditions.
Bench testing of the injectors can only be done using expensive special equipment. Generally this equipment can be found at a dealership and sometimes at a well-equipped machine or performance shop. There is no provision for field testing the injectors by the owner/mechanic. DO NOT attempt to test the injector by removing it from the engine and making it spray into a jar.
Never attempt to check a removed injector by hooking it directly to the battery. The injector runs on a smaller voltage and the 12 volts from the battery will destroy it internally.