Chrysler Caravan/Voyager/Town n Country 1984-1995

General Information

Print

This electronic fuel injection system is a computer regulated single point fuel injection system that provides precise air/fuel ratio for all driving conditions. At the center of this system is a digital pre-programmed computer also known as an engine controller or Powertrain Control Module (PCM), that regulates ignition timing, air/fuel ratio, emission control devices, idle speed and cooling fan and charging system. This component has the ability to update and revise its programming to meet changing operating conditions.

Various sensors provide the input necessary for the PCM to correctly regulate the fuel flow at the fuel injector. These include the manifold absolute pressure, throttle position, oxygen sensor, coolant temperature, vehicle speed (distance) sensors and throttle body temperature. In addition to the sensors, various switches also provide important information. These include the neutral-safety switch, air conditioning clutch relay, and auto shut-down relay.

All inputs to the PCM are converted into signals which are used by the computer. Based on these inputs, air/fuel ratio, ignition timing or other controlled outputs are adjusted accordingly.

The PCM tests many of its own input and output circuits. If a fault is found in a major system this information is stored in the memory. Information on this fault can be displayed to a technician by means of the instrument panel check engine light or by connecting a diagnostic read out and reading a numbered display code which directly relates to a specific fault.

SERVICE PRECAUTIONS



When working around any part of the fuel system, take precautionary steps to prevent possible fire and/or explosion:



Disconnect the negative battery terminal, except when testing with battery voltage is required.
 
Whenever possible, use a flashlight instead of a drop light to inspect fuel system components or connections.
 
Keep all open flames and smoking material out of the area and make sure there is adequate ventilation to remove fuel vapors.
 
Use a clean shop cloth to catch fuel when opening a fuel system. Dispose of gasoline-soaked rags properly.
 
Relieve the fuel system pressure before any service procedures are attempted that require disconnecting a fuel line.
 
Use eye protection.
 
Always keep a dry chemical (class B) fire extinguisher near the area.
 

DIAGNOSIS & TESTING



Mechanical malfunctions are more difficult to diagnose with the EFI system. The PCM has been programmed to compensate for some mechanical malfunctions such as incorrect cam timing, vacuum leaks, etc. If engine performance problems are encountered, and no fault codes are displayed, the problem may be mechanical rather than electronic. Refer to Driveability & Emissions Controls for additional information on accessing and reading diagnostic codes

VISUAL INSPECTION



A visual inspection for loose, disconnected or misrouted wires and hoses should be made before attempting to diagnose or service the fuel injection system. A visual check will help spot these faults and save unnecessary test and diagnostic time. A thorough visual inspection will include the following checks:

  1. Check that vacuum connections on rear and/or front of throttle body are secure and not leaking.
  2.  
  3. Check that vacuum connection(s) at EGR and/or purge solenoid is secure and not leaking.
  4.  
  5. Check that hoses are securely attached to vapor canister.
  6.  
  7. Check that hose from PCV valve is securely attached to the intake manifold vacuum port.
  8.  
  9. Check that hoses are attached to back-pressure transducer.
  10.  
  11. Check that alternator wiring and belt are correctly installed and tight.
  12.  
  13. Check that heated air door vacuum connection is connected and not leaking.
  14.  
  15. Check vacuum connections at MAP sensor.
  16.  
  17. Check that hose and wiring connections at the fuel pump are tight and wires are making contact with the terminals on pump.
  18.  
  19. Check power brake and speed control vacuum connections are tight.
  20.  
  21. Check that the following electrical connections are clean, tight and have good contact:
    1. Connectors to the PCM
    2.  
    3. Connector at EGR solenoid and/or purge solenoid
    4.  
    5. Connector at speed (distance) sensor
    6.  
    7. Connector at cooling fan relay
    8.  
    9. Connector to oxygen sensor
    10.  
    11. Connector at fuel injector(s)
    12.  
    13. Connector at Automatic Idle Speed (AIS) and Throttle Position Sensor (TPS)
    14.  
    15. Connector at coolant temperature sensor
    16.  
    17. Connector at throttle body temperature sensor
    18.  
    19. Connector to distributor
    20.  
    21. Connectors for engine-to-main harness
    22.  
    23. Connectors for all relays
    24.  
    25. Connector to neutral safety switch (automatic only)
    26.  
    27. All ignition cables are in order and seated
    28.  
    29. Ground straps to engine and dash panel
    30.  
    31. Connection to battery
    32.  

  22.  

FUEL SYSTEM PRESSURE TEST



1987-91 Models


CAUTION
Fuel system pressure must be released as previously described each time a fuel hose is to be disconnected. Take precautions to avoid the risk of fire.

  1. Remove fuel intake hose from throttle body and connect fuel system pressure testers C-3292, and C-4749, or equivalent, between fuel filter hose and throttle body.
  2.  
  3. Start engine and read gauge. Pressure should be 14.5 psi (100 kPa).
  4.  

ATM tester C-4805 (or equivalent) can be used. With ignition in RUN, depress ATM button. This activate the fuel pump and pressure system

  1. If fuel pressure is below specifications:
    1. Install tester between fuel filter hose and fuel line.
    2.  
    3. Start engine. If pressure is now correct, replace fuel filter. If no change is observed, gently squeeze return hose. If pressure increases, replace pressure regulator. If no change is observed, problem is either a plugged pump filter sock or defective fuel pump.
    4.  

  2.  
  3. If pressure is above specifications:
    1. Remove fuel return hose from throttle body. Connect a substitute hose and place other end of hose in clean container.
    2.  
    3. Start engine. If pressure is now correct, check for restricted fuel return line. If no change is observed, replace fuel regulator.
    4.  

  4.  

1991-95 Models

CAUTION
Fuel system pressure must be released as previously described each time a fuel hose is to be disconnected. Take precautions to avoid the risk of fire.

  1. Release the fuel system pressure as outlined below.
  2.  
  3. Remove the fuel supply hose quick connector from the chassis lines (at the engine).
  4.  
  5. Connect fuel pressure Gauge C-4799 (or equivalent) to the Fuel Pressure Test Adapter 6539. Install the adapter between the fuel supply hose and the chassis fuel line assembly.
  6.  


CAUTION
When using the ASD Fuel System Test, the ASD relay and fuel pump relay remain energized for 7 minutes, until the test is stopped, or until the ignition switch is turned to the OFF position.

  1. Place the ignition key to the ON position. Using the DRB II scan tool, access the ASD Fuel System Test. The ASD Fuel System Test will activate the fuel pump and pressurize the system. If the gauge reads 39 psi (269 kPa), further testing is not required. If the pressure is not correct, record the pressure and remove the gauge.
  2.  
  3. If the fuel pressure reading was below specifications, proceed to next step.
  4.  
  5. Perform the fuel pressure release procedure.
  6.  
  7. Remove the fuel supply hose quick connector from the chassis lines (at the engine).
  8.  
  9. Connect fuel pressure Gauge C-4799 and Fuel Pressure Adapter 6433 (or equivalents) in the fuel supply fuel line between the fuel tank and the fuel filter.
  10.  
  11. Using the DRB II scan tool, with the ignition key in the ON position, repeat the ASD Fuel System Test.
  12.  
  13. If the pressure is at least 5 psi (34 kPa) higher than the reading recorded earlier, replace the fuel filter.
  14.  
  15. If no change is observed, gently squeeze the return hose. If the gauge reading does not change when the return hose is squeezed, the problem is either a plugged inlet strainer or defective fuel pump.
  16.  
  17. If the fuel pressure reading was above specifications in Step 4, proceed to next step.
  18.  
  19. Perform the fuel pressure release procedure.
  20.  
  21. Connect fuel pressure Gauge C-4799 and Fuel Pressure Adapter 6433 (or equivalents) in the fuel supply fuel line between the fuel tank and the fuel filter.
  22.  
  23. Remove the fuel return hose from the fuel pump at the fuel tank. Connect the Fuel Pressure Test Adapter 6541 to the return line. Place the other end of adapter 6541 into an approved gasoline container (minimum 2 gallon/7.5 liters size). All return fuel will flow into the container.
  24.  
  25. Using the DRB II scan tool (or equivalent), with the ignition key in the ON position, repeat the ASD Fuel System Test.
  26.  
  27. If the pressure is now correct, replace the fuel pump assembly.
  28.  
  29. If the pressure is still above specifications, remove the fuel return hose from the chassis fuel tubes at engine.
  30.  
  31. Connect the Fuel Pressure Test Adapter 6541 to the return line. Place the other end of adapter 6541 into an approved gasoline container. Repeat the test. If pressure is now correct, check for a restricted fuel return line. If no change is observed, replace the fuel pressure regulator.
  32.  

FUEL SYSTEM PRESSURE RELEASE




CAUTION
The fuel injection system is under a constant pressure of approximately 14.5 psi (100 kPa). Before servicing any part of the fuel injection system, the system pressure must be released. Use a clean shop towel to catch any fuel spray and take precautions to avoid the risk of fire.

  1. Loosen gas cap to release tank pressure.
  2.  
  3. Remove wiring harness connector from injector.
  4.  
  5. Ground 1 terminal of the injector harness.
  6.  
  7. Connect jumper wire to positive second terminal of the harness and touch battery positive post for no longer than 10 seconds. This releases system pressure.
  8.  
  9. Remove jumper wire and continue fuel system service.
  10.  

 
label.common.footer.alt.autozoneLogo