Mazda Trucks 1987-1993 Repair Guide

Fuel Charging Assembly

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REMOVAL & INSTALLATION



4-Cylinder Engines

To remove the fuel charging (fuel rail) assembly, refer to the fuel injector removal procedure earlier in this section.

3.0L Engine

See Figures 1, 2 and 3

  1. Perform fuel system pressure release procedure. Refer to fuel system pressure release procedure in this section.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Loosen clamps securing air cleaner to throttle body hose and remove hose.
  6.  
  7. Remove the throttle cable and transaxle kickdown linkage.
  8.  
  9. Remove harness connector from throttle position sensor (TPS), and automatic idle speed (AIS) motor.
  10.  
  11. Label and remove vacuum hoses from throttle body. Remove PCV and brake booster hoses from air intake plenum.
  12.  
  13. Remove EGR tube to intake plenum.
  14.  
  15. Remove electrical connection from charge temperature and coolant temperature sensor.
  16.  
  17. Remove vacuum connection from pressure regulator and air intake connection from manifold.
  18.  
  19. Remove fuel hoses to fuel rail connection.
  20.  
  21. Remove air intake plenum to manifold bolts (8) and remove air intake plenum and gaskets.
  22.  


WARNING
Whenever air intake plenum is remove, cover intake manifold properly to avoid objects from entering cylinder head.

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Fig. Fig. 1: Fuel system components



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Fig. Fig. 2: Fuel injector wiring harness locations



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Fig. Fig. 3: Fuel pressure regulator removal/installation


  1. Disconnect fuel injector wiring harness from engine wiring harness.
  2.  
  3. Remove pressure regulator attaching bolts and remove pressure regulator from rail.
  4.  
  5. Remove fuel rail attaching bolts and remove fuel rail.
  6.  

To install:
  1. Make certain injector are properly seated in receiver cup with lock rings in place and injector discharge holes are clean.
  2.  
  3. Lubricate injector O-rings with a clean drop of engine oil.
  4.  
  5. Install injector rail assembly making sure each injector seats in their respective ports. Tighten the fuel rail attaching bolts to 115 inch lbs. (13 Nm).
  6.  
  7. Lubricate pressure regulator O-ring with a drop of clean engine oil and install regulator to fuel rail. Tighten the nuts to 77 inch lbs. (9 Nm).
  8.  
  9. Install hold down bolts on fuel supply and return tube, and vacuum crossover tube.
  10.  
  11. Install and tighten the fuel pressure regulator hose clamps to 10 inch lbs. (1 Nm).
  12.  
  13. Reconnect injector wiring harness.
  14.  
  15. Reconnect vacuum hoses to fuel pressure regulator and fuel rail.
  16.  
  17. Set the air intake plenum gasket in place with beaded sealer in the up position.
  18.  
  19. Install air intake plenum and tighten (8) attaching screws to 115 inch lbs. (13 Nm).
  20.  
  21. Reconnect fuel line to fuel rail and tighten clamps to 10 inch lbs. (1 Nm).
  22.  
  23. Reconnect EGR tube to intake plenum and torque nuts to 200 inch lbs. (23 Nm).
  24.  
  25. Reconnect electrical wiring to charge temperature sensor, coolant temperature sensor, TPS and AIS motor.
  26.  
  27. Reconnect vacuum connection to throttle body and air intake plenum.
  28.  
  29. Install accelerator cable and transaxle kickdown cable.
  30.  
  31. Install air cleaner to throttle body hose and tighten clamps.
  32.  
  33. Reconnect battery negative cable.
  34.  

4.0L Engine

See Figures 4 and 5

  1. Disconnect the battery ground cable.
  2.  
  3. Remove the air cleaner and intake duct.
  4.  
  5. Remove the linkage shield.
  6.  
  7. Disconnect the throttle cable and bracket.
  8.  
  9. Tag and disconnect all vacuum lines connected to the manifold.
  10.  
  11. Tag and disconnect all electrical wires connected to the manifold assemblies.
  12.  
  13. Relieve the fuel system pressure.
  14.  


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. Tag and remove the spark plug wires.
  2.  
  3. Remove the EDIS ignition coil and bracket.
  4.  
  5. Remove the throttle body and discard the gasket.
  6.  



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Fig. Fig. 4: Upper intake manifold removal/installation



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Fig. Fig. 5: Fuel supply manifold assembly

  1. Remove the 6 attaching nuts and lift off the upper manifold.
  2.  
  3. Disconnect the fuel supply line at the fuel supply manifold.
  4.  
  5. Disconnect the fuel return line at the pressure regulator as follows:
    1. Disengage the locking tabs on the connector retainer and separate the retainer halves.
    2.  
    3. Check the visible, internal portion of the fitting for dirt. Clean the fitting thoroughly.
    4.  
    5. Push the fitting towards the regulator, insert the fingers on Fuel Line Coupling Key T90P-9550-A, or equivalent, into the slots in the coupling. Using the tool, pull the fitting from the regulator. The fitting should slide off easily, if properly disconnected.
    6.  

  6.  
  7. Remove the 6 Torx® head stud bolts retaining the manifold and remove the manifold.
  8.  
  9. Remove the electrical harness connector from each injector.
  10.  
  11. If required, remove the fuel injectors.
  12.  

To install:
  1. If removed, install the fuel injectors into the fuel supply manifold.
  2.  
  3. Install the retainers and electrical harness connectors.
  4.  
  5. Position the fuel supply manifold and press it down firmly until the injectors are fully seated in the fuel supply manifold and lower intake manifold.
  6.  
  7. Install the 6 Torx® head bolts and tighten them to 7-10 ft. lbs. (9-14 Nm).
  8.  
  9. Install the fuel supply line and tighten the fitting to 15-18 ft. lbs. (20-24 Nm).
  10.  
  11. Install the fuel return line on the regulator by pushing it onto the fuel pressure regulator line of to the shoulder.
  12.  


WARNING
The connector should grip the line securely!

  1. Install the connector retainer and snap the two halves of the retainer together.
  2.  
  3. Install the upper manifold. Tighten the nuts to 18 ft. lbs. (24 Nm).
  4.  
  5. Install the EDIS coil.
  6.  
  7. Connect the fuel and return lines.
  8.  
  9. Ensure that the mating surfaces of the throttle body and upper manifold are clean and free of gasket material.
  10.  
  11. Install the throttle body assembly.
  12.  
  13. Connect all wires.
  14.  
  15. Connect all vacuum lines.
  16.  
  17. Connect the throttle linkage.
  18.  
  19. Install the linkage shield.
  20.  
  21. Install the air cleaner and duct.
  22.  
  23. Fill and bleed the cooling system.
  24.  
  25. Connect the battery ground.
  26.  
  27. Run the engine and check for leaks.
  28.  

 
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