Toyota Corolla 1970-1987 Repair Guide

Fuel Injectors

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There is one fuel injector for each cylinder. They spray fuel in front of the intake valve. The injectors are electrically triggered valves which deliver a measured quantity of fuel into the intake manifold according to signals from the ECU. As driving conditions change, the computer signals each injector to remain open a longer or shorter period of time, thus controlling the amount of fuel introduced into the engine. Being an electric component, an injector is either on or off (open or closed); there is no variable control for an injector other than duration.

Cleanliness equals success 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 miniaturized and solid state circuitry is easily damaged by a jolt. Additionally, care must be used in dealing with electrical connectors. Look for and release any locking mechanisms on the connector before separating the connectors. When reattaching, make sure each pin is properly lined up and seated before pushing the connector closed.

REMOVAL & INSTALLATION



See Figures 1, 2 and 3

  1. Disconnect the negative battery cable. Relieve the fuel pressure.
  2.  
  3. Remove the cold start injector pipe.
  4.  

Be sure to have a suitable container on hand to catch any dripping fluid



Click image to see an enlarged view

Fig. Fig. 1: Partial exploded view of the fuel rail/injector assembly

  1. Remove the air intake pipes, if necessary.
  2.  
  3. Disconnect the fuel inlet line from the delivery pipe. Tag and disconnect the vacuum sensing hose and the fuel return line from the pressure regulator.
  4.  
  5. Remove the two plastic EFI solenoid wiring harness clamps, then tag and disconnect the wiring connectors from the tops of the fuel injectors.
  6.  
  7. Unscrew the three nuts, then remove the delivery pipe with the injectors attached.
  8.  

Be careful not to drop the injectors when removing the delivery pipe. Do not remove the cover

To install:
  1. Insert four new insulators into the injector holes on the intake manifold.
  2.  



Click image to see an enlarged view

Fig. Fig. 2: Be sure to insert the injector into the fuel delivery pipe properly



Click image to see an enlarged view

Fig. Fig. 3: View of a properly installed fuel injector

  1. Install the grommet and a new O-ring to the delivery pipe end of each injector.
  2.  
  3. Apply a thin coat of gasoline to the O-ring on each injector, then press them into the delivery pipe.
  4.  
  5. Install the injectors together with the delivery pipe to the intake manifold. Tighten the mounting bolts to 11-15 ft. lbs. (15-20 Nm).
  6.  
  7. Installation of the remaining components is in the reverse order of removal.
  8.  
  9. Start the engine and check for any fuel leaks.
  10.  

TESTING



The simplest way to test the injectors is simply to listen to them with the engine running. Use either a stethoscope-type tool or the blade of a long screw driver to touch each injector while the engine is idling. You should hear or feel 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 remove the electrical connector from the injector to be tested. Use an ohmmeter to check the resistance across the terminals of the injector. Correct ohmage is approximately 13.8 ohms 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 much smaller voltage and the 12 volts from the battery will destroy it internally.

 
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