Toyota Corolla 1988-1997 Repair Guide

Fuel Injectors

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See Figure 1

The injectors deliver a measured quantity of fuel into the intake manifold 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, thus controlling the amount of fuel introduced into the engine. An injector, being an electric component, is either on or off (open or closed); there is no variable control for an injector other than duration.



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Fig. Fig. 1: Cutaway view of a common fuel injector

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



4A-GE Engine

See Figures 2 through 7


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Disconnect the negative battery cable.
  2.  

If you are diagnosing a driveability problem, check the ECM for any stored trouble codes BEFORE disconnecting the cable. The codes will be lost after the battery is disconnected.

  1. Disconnect the PCV hose from the valve cover.
  2.  
  3. Remove the vacuum sensing hose from the pressure regulator.
  4.  
  5. Disconnect the fuel return hose from the pressure regulator.
  6.  
  7. Place a towel or container under the cold start injector pipe. Loosen the two union bolts at the fuel line and remove the pipe with its gaskets.
  8.  



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Fig. Fig. 2: Unbolt and remove the fuel rail

  1. Remove the fuel inlet pipe mounting bolt and disconnect the fuel inlet hose by removing the fuel union bolt, the two gaskets and the hose.
  2.  
  3. Disconnect the injector electrical wiring.
  4.  
  5. At the fuel delivery pipe (rail), remove the three bolts. Lift the delivery pipe and the injectors free of the engine. DON'T drop the injectors.
  6.  
  7. Remove the four insulators and three collars from the cylinder head.
  8.  
  9. Pull the injectors free of the delivery pipe.
  10.  

To install:
  1. Before installing the injectors back into the fuel rail, install a NEW O-ring on each injector.
  2.  



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Fig. Fig. 3: When replacing an injector, always install a new O-ring



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Fig. Fig. 4: The fuel injectors must be installed properly into the fuel rail

  1. Coat each O-ring with a light coat of gasoline (NEVER use oil of any sort) and install the injectors into the delivery pipe. Make certain each injector can be smoothly rotated. If they do not rotate smoothly, the O-ring is not in its correct position.
  2.  
  3. Install the insulators into each injector hole. Place the three spacers on the delivery pipe mounting holes in the cylinder head.
  4.  



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Fig. Fig. 5: Make sure the injectors rotate smoothly



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Fig. Fig. 6: Make sure the insulators and spacers are correctly positioned on the cylinder head

  1. Place the delivery pipe and injectors on the cylinder head and again check that the injectors rotate smoothly. Install the three bolts and tighten them to 13 ft. lbs. (17 Nm).
  2.  



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Fig. Fig. 7: Once the injectors are installed, again make sure they rotate smoothly

  1. Connect the electrical connectors to each injector.
  2.  
  3. Install two new gaskets and attach the inlet pipe and fuel union bolt. Tighten the bolt to 22 ft. lbs. (30 Nm). Install the mounting bolt.
  4.  
  5. Install new gaskets and connect the cold start injector pipe to the delivery pipe and cold start injector. Install the fuel line union bolts and tighten them to 13 ft. lbs. (17 Nm).
  6.  
  7. Connect the fuel return hose and the vacuum sensing hose to the pressure regulator. Attach the PCV hose to the valve cover.
  8.  
  9. Connect the battery cable to the negative battery terminal. Start the engine and check for leaks.
  10.  


CAUTION
If there is a leak at any fitting, the line will be under pressure and the fuel may spray in a fine mist. This mist is extremely explosive. Shut the engine off immediately if any leakage is detected. Use rags to wrap the leaking fitting until the pressure diminishes and wipe up any fuel from the engine area.

4A-FE Engine
1990-92 MODELS
  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the PCV hose from the valve cover.
  4.  
  5. Remove the vacuum sensing hose from the pressure regulator.
  6.  
  7. Disconnect the fuel return hose from the pressure regulator.
  8.  
  9. Place a towel or container under the cold start injector pipe. Loosen the two union bolts at the fuel line and remove the pipe with its gasket.
  10.  
  11. Remove the fuel inlet pipe mounting bolt and disconnect the fuel inlet hose by removing the fuel union bolt, the two gaskets and the hose.
  12.  
  13. Disconnect the injector electrical connection.
  14.  
  15. At the fuel delivery pipe (rail), remove the two bolts. Lift the delivery pipe and the injectors free of the engine. DON'T drop the injector.
  16.  
  17. Remove the 4 insulators and 2 collars from the cylinder head.
  18.  
  19. Pull the injectors free of the delivery pipe.
  20.  

To install:
  1. Before installing the injectors back into the fuel rail, install a NEW O-ring on each injector.
  2.  
  3. Coat each O-ring with a light coat of gasoline (NEVER use oil of any sort) and install the injectors into the delivery pipe. Make certain each injector can be smoothly rotated. If they do not rotate smoothly, the O-ring is not in its correct position.
  4.  
  5. Install the insulators into each injector hole. Place the two spacers on the delivery pipe mounting holes in the cylinder head.
  6.  
  7. Place the delivery pipe and injectors on the cylinder head and again check that the injectors rotate smoothly. Install the two bolts and tighten them to 11 ft. lbs. (15 Nm)
  8.  
  9. Connect the electrical connectors to each injector.
  10.  
  11. Install two new gaskets and attach the inlet pipe and fuel union bolt. Tighten the bolt to 22 ft. lbs. (30 Nm). Install the mounting bolt.
  12.  
  13. Install new gaskets and connect the cold start injector pipe to the delivery pipe and cold start injector. Install the fuel line union bolts and tighten them to 13 ft. lbs. (17 Nm).
  14.  
  15. Connect the fuel return hose and the vacuum sensing hose to the pressure regulator. Attach the PCV hose to the valve cover.
  16.  
  17. Connect the battery cable to the negative battery terminal. Start the engine and check for leaks.
  18.  

4A-FE and 7A-FE Engines
1993-97 MODELS

See Figures 8, 9 and 10

  1. Disconnect the negative battery cable.
  2.  



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Fig. Fig. 8: Fuel injectors are attached to the side of the fuel rail


CAUTION
On models with an airbag, wait at least 90 seconds from the time that the ignition switch is turned to the LOCK position and the battery is disconnected before performing any further work. Refer to Drive Train for all air bag warnings.

  1. Relieve the fuel pressure.
  2.  
  3. Remove the air cleaner hose and cap.
  4.  
  5. Disconnect the accelerator cable bracket from the throttle body.
  6.  
  7. Disconnect the throttle body from the air intake chamber. Using a 6mm hexagon wrench, remove the 3 bolts and 2 nuts, then disconnect the throttle body and chamber cover assembly from the intake manifold. Remove and discard the gasket.
  8.  
  9. Remove the engine hanger and air intake chamber stay and EGR vacuum modulator if so equipped.
  10.  
  11. Remove the EGR valve and pipe if so equipped.
  12.  
  13. Remove all necessary hoses/electrical connections.
  14.  



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Fig. Fig. 9: Label and disconnect the wiring to each injector

  1. Separate the injector electrical wiring.
  2.  
  3. Detach the fuel inlet hose from the delivery pipe.
  4.  
  5. Disconnect the fuel return hose from the fuel pressure regulator.
  6.  



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Fig. Fig. 10: Remove the vacuum and return hoses from the pressure regulator

  1. At the fuel delivery pipe (rail), remove the two bolts. Lift the delivery pipe and the injectors free of the engine. DON'T drop the injectors.
  2.  
  3. Remove the 4 insulators and 2 collars from the intake manifold. Pull the injectors free of the delivery pipe.
  4.  
  5. Remove the O-rings and grommet from each of the injectors and discard.
  6.  

To install:
  1. Before installing the injectors back into the fuel rail, install a NEW O-ring on each injector.
  2.  
  3. Coat each O-ring with a light coat of gasoline (NEVER use oil of any sort) and install the injectors with a turning motion into the delivery pipe. Make certain each injector can be smoothly rotated. If they do not rotate smoothly, the O-ring is not in its correct position.
  4.  
  5. Install the insulators into each injector hole. Place the two spacers on the delivery pipe mounting holes in the intake manifold.
  6.  
  7. Place the delivery pipe and injectors on the intake manifold and again check that the injectors rotate smoothly. Position the injector connector upward. Install the two bolts and tighten them to 11 ft. lbs. (15 Nm).
  8.  

The No. 1 and No. 3 injector connections are gray and the No. 2 and No. 4 injector connections are dark gray.

  1. Connect the electrical wiring to each injector.
  2.  
  3. Install two new gaskets and attach the inlet pipe and fuel union bolt. Tighten the bolt to 22 ft. lbs. (30 Nm). Install the mounting bolt.
  4.  
  5. Install the air intake chamber cover with a NEW gasket. Tighten the retaining bolts in steps to 14 ft. lbs. (19 Nm).
  6.  
  7. Install all necessary hoses and electrical connections.
  8.  
  9. Install the EGR valve and pipe if so equipped.
  10.  
  11. Install the engine hanger and air intake chamber stay and EGR vacuum modulator if so equipped.
  12.  
  13. Install a new gasket on the air intake chamber stay, facing the protrusion downward. Install the throttle body and tighten the bolts evenly (in a X-pattern) to 16 ft. lbs. (21 Nm).
  14.  
  15. Connect the accelerator cable bracket to the throttle body.
  16.  
  17. Install the air cleaner hose and cap.
  18.  
  19. Connect the battery cable to the negative battery terminal. Start the engine and check for leaks.
  20.  

TESTING



See Figure 11

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 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 ohmmage is approximately 13.8 ohms at 68°F (20°C); slight variations are acceptable due to temperature conditions.



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Fig. Fig. 11: Fuel injector testers can be purchased or sometimes rented

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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