Chrysler RAM50/D50/Arrow 1979-1993 Repair Guide

Fuel Rail and Injectors

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REMOVAL & INSTALLATION




WARNING
The injectors are extremely sensitive to dirt and impact. They must be handled gently and protected at all times. The entire work area must be as clean as possible. Any particle of dirt entering the system can foul an injector or change its operation. Any gaskets or O-rings removed with the injector MUST be replaced with new ones at reassembly. Do not attempt to reuse these seals; high pressure fuel leaks may result. See Figure 1



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Fig. Fig. 1: Cross-sectional view of a typical MFI fuel injector

2.4L Engines See Figures 2 and 3

  1. Safely relieve the pressure within the fuel system-refer to the procedures described previously in this section.
  2.  



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Fig. Fig. 2: Make certain that the intake manifold-to-throttle body gasket is in the correct position-2.4L engines



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Fig. Fig. 3: Fuel injector location and assembly components-2.4L engines


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.  
  3. Drain the engine coolant to a level below that of the intake manifold.
  4.  
  5. Remove the air intake hose, the breather hose, the wiring harness connector, the air intake pipe and the air hose.
  6.  
  7. Disconnect the accelerator and kickdown cables from the throttle body.
  8.  
  9. Remove the water and vacuum hoses from the throttle body.
  10.  
  11. Remove the throttle body from the intake manifold plenum. Refer to the procedures described previously in this section.
  12.  
  13. Extract the gasket from the throttle body/intake manifold plenum mounting surface; a new gasket will be needed upon assembly.
  14.  
  15. Unplug the fuel injector wiring harness from the fuel injectors.
  16.  
  17. Disconnect the high pressure fuel line from the fuel rail.
  18.  


WARNING
There may still be residual pressure in the fuel system; release the fuel line slowly to allow pressure to escape. Have rags handy to wipe or soak up any spilled fuel.

  1. Remove the fuel return hose, the mounting bolt and the fuel pressure regulator from the fuel rail. The O-ring between the fuel rail and the fuel pressure regulator will need to be replaced with a new one upon assembly.
  2.  
  3. Remove the fuel rail with the fuel injectors installed.
  4.  

The fuel injectors are extremely sensitive to contaminants, impact or wrong voltages. Do not allow any of the injectors to fall when removing the fuel rail. If an injector does drop to the floor or other hard surface, it should be replaced.

  1. Remove the fuel rail to intake manifold insulators.
  2.  
  3. Remove the injectors (with a slight pull), the O-rings, the grommets and the insulators from the fuel rail. The O-rings, the grommets and the insulators must all be replaced with new ones upon assembly.
  4.  

To install:
  1. Reassembly begins by installing a new grommet and O-ring (in that order) onto the injector. Coat the O-ring with a light coating of oil.
  2.  
  3. Install each injector into the rail by turning it to the left and right. Make sure that the injector turns freely when in place. If it does not turn under finger pressure, remove it, inspect the O-ring and reinsert the injector. While the injector does not turn during its operation, its ability to turn is an indicator of correct installation.
  4.  
  5. Replace the seats (insulator) in the intake manifold. Install the delivery pipe and the injectors onto the manifold without dropping an injector. Make certain the rubber bushings are correctly seated in the installation holes.
  6.  
  7. Install a new O-ring on the fuel pressure regulator and coat it lightly with clean gasoline. Install and tighten the fuel pressure regulator to fuel rail mounting bolts to 5-8 ft. lbs. (7-11 Nm).
  8.  
  9. Install the fuel rail mounting bolts through the fuel return hose mounting bracket, through the fuel rail and into the intake manifold. Tighten them to 6-9 ft. lbs. (8-12 Nm).
  10.  
  11. Connect the fuel return hose to the fuel return rail. Fasten it in place with the spring clip.
  12.  
  13. Connect the high pressure fuel line to the fuel rail, using as new O-ring. Coat the O-ring with a little gasoline to help it seal better. Tighten the two retaining bolts to 1-2 ft. lbs. (2-3 Nm).
  14.  
  15. Plug the fuel injector harness back onto the fuel injectors.
  16.  
  17. Install the throttle body back onto the intake manifold plenum with a new gasket. Make sure the gasket goes onto the intake manifold plenum to throttle body opening with the gasket projection up and to the left (look straight into the intake manifold plenum opening, in other words from the passenger-side of the engine compartment). Install the throttle body mounting bolts with 11-16 ft. lbs. (15-22 Nm) of torque.
  18.  
  19. Connect the vacuum hose, the water hose, the automatic transmission kickdown cable (if so equipped) and the accelerator cable. Refer to the accelerator cable adjustment procedure described earlier in this section.
  20.  
  21. Connect the air hose, the air intake pipe, the breather hose and the air intake hose.
  22.  
  23. Plug the wiring harness connector back into the throttle body.
  24.  
  25. Fill the engine coolant system back up.
  26.  
  27. Connect the negative (-) battery cable back to the battery and start the engine. The engine may turn over a few times until the fuel system pressure can be brought back up to normal.
  28.  
  29. Check for any coolant or fuel leaks, repair if necessary.
  30.  

3.0L Engine See Figures 4, 5 and 6

  1. Safely relieve the pressure within the fuel system.
  2.  


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.  
  3. Remove the air intake plenum, following procedures listed in Engine And Engine Overhaul .
  4.  
  5. Disconnect the high pressure fuel line at the delivery pipe (rail). The O-ring inside the fitting is not reusable.
  6.  


WARNING
Have a clean rag or towel handy to catch the residual gasoline in the fuel system. Some pressure will remain within the system.

  1. Disconnect the fuel return hose and remove its O-ring. Disconnect the vacuum hose from the fuel pressure regulator.
  2.  
  3. Remove the fuel pressure regulator and its O-ring.
  4.  
  5. Remove the cover piece from the fuel rail, if so equipped.
  6.  
  7. Unplug the electrical connector from each injector.
  8.  
  9. Remove the bolts holding the delivery pipe to the engine. Note that the fuel rail is one continuous piece serving both banks of cylinders.
  10.  
  11. Lift the rail with the injectors attached up and away from the engine. Take great care not to drop any of the injectors during this removal.
  12.  

The fuel injectors are extremely sensitive to contaminants, impact or wrong voltages. Do not allow any of the injectors to fall when removing the fuel rail. If an injector does drop to the floor or other hard surface, it should be replaced.

  1. The injectors may be removed from the rail with a gentle pull. Both the grommet (insulator) and O-ring on the top of the injector must be discarded and replaced. The lower insulator or seat must also be removed and replaced.
  2.  


WARNING
Some fuel will flow out of the delivery pipe when the injectors are removed.



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Fig. Fig. 4: Fuel injector location and assembly components



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Fig. Fig. 5: Attach 6 new injector insulators and 4 new delivery pipe insulators to the intake manifold



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Fig. Fig. 6: When securing the delivery pipe, confirm that the insulators are properly situated rented

  1. Reassembly begins by installing a new grommet and O-ring (in that order) onto the injector. Coat the O-ring with a light coating of clean engine oil.
  2.  

Use care not to let the engine oil enter the delivery pipe.

  1. Install each injector into the rail, making sure that the injector turns freely when in place. If it does not turn under finger pressure, remove it, inspect the O-ring and reinsert the injector. (While the injector does not turn during its operation, its ability to turn is an indicator of correct installation).
  2.  
  3. Replace the seats (insulators) in the intake manifold. Install new rubber bushings onto the mounting points of the fuel rail. Install the delivery pipe and the injectors onto the manifold without dropping an injector. Make certain the rubber bushings are in place under the delivery pipe brackets.
  4.  
  5. Tighten the fuel rail bolts to 9 ft. lbs. (12 Nm).
  6.  
  7. Plug each electrical connector onto its proper injector.
  8.  
  9. Install the cover on the fuel rail (if so equipped); tighten the bolts to 6 ft. lbs. (8 Nm).
  10.  
  11. Replace the O-ring, coat it lightly with gasoline and install the fuel pressure regulator. Tighten the fasteners to 7 ft. lbs. (9 Nm).
  12.  
  13. Connect the fuel return hose and any vacuum hoses.
  14.  
  15. Install the new O-ring, coat it lightly with gasoline and install the high pressure fuel line. Make certain the O-ring is not damaged during installation. Tighten the bolts to 1.5-2 ft. lbs. (2-3 Nm).
  16.  
  17. Reinstall the air intake plenum; refer to Engine And Engine Overhaul of this repair guide for the removal and installation procedure.
  18.  
  19. Reattach any component removed earlier.
  20.  
  21. Connect the negative battery cable.
  22.  

TESTING



See Figure TCCS5P03

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 screwdriver to touch each injector while the engine is idling. You should hear a distinct clicking as each injector opens and closes. Check that the operating sound increases as the engine speed is increased.

The sounds of the other injector(s) may be heard, even though the one being checked is not operating. Listen to each injector to get a feel for normal sounds; the one with the abnormal sound is the problem.

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 resistance at 68°F (20°C) is 13-16 ohms.

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 shop 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.

Fuel injector testers can be purchased or sometimes rented

Click image to see an enlarged view

Fig. Fig. 6: When securing the delivery pipe, confirm that the insulators are properly situated 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. Since this happens at the speed of electricity, you don't get a second chance.

For diagnostic procedures and trouble codes regarding the Electronic Control Module (ECM) and MFI system, refer to Emission Controls of this guide.

 
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