Mazda Trucks 1972-1986 Repair Guide

Injection Pump

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REMOVAL & INSTALLATION



See Figures 1, 2 and 3

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Fig. Fig. 1: Diesel Fuel System Troubleshooting



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Fig. Fig. 2: Injection pump attaching locations



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Fig. Fig. 3: Installing the injection pump timing gauge

  1. Disconnect both battery ground cables.
  2.  
  3. Remove the radiator fan and shroud.
  4.  
  5. Remove the air conditioning compressor/power steering drive belt and idler pulley.
  6.  
  7. Remove the injection pump cover and gasket.
  8.  
  9. Turn the crankshaft until the injection pump drive gear keyway is at TDC.
  10.  
  11. Remove the large nut and washer attaching the drive gear to the injection pump.
  12.  

Be careful! It's easy to accidentally drop the washer into the timing case.

  1. Remove the intake hose from the air cleaner and manifold.
  2.  
  3. Disconnect the throttle cable and, if equipped, the cruise control cable, from the pump.
  4.  
  5. Disconnect the fuel inlet line from the pump. Cap the line and pump fitting immediately.
  6.  
  7. Disconnect the fuel shut-off solenoid lead at the pump.
  8.  
  9. Disconnect the injection lines from the nozzle and pump. Cap the lines, nozzles and pump openings immediately.
  10.  
  11. Disconnect the lower fuel return line at the pump and fuel hoses. Cap all openings.
  12.  
  13. Loosen the lower no.3 intake port nut and remove the fuel return line.
  14.  
  15. Remove the two nuts attaching the injection pump to the front timing gear cover, and the one bolt attaching the pump to the rear support bracket.
  16.  
  17. Install a gear and hub remover in the drive gear cover and attach it to the injection pump drive gear. Rotate the screw clockwise until the gear separates from the pump. Remove the pump.
  18.  

When removing the pump, be careful to avoid dropping the pump shaft key into the timing case. Disconnect the cold start cable before lifting the pump clear of the engine, and reconnect it when lowering the pump into place for installation.

To install:
  1. Install the pump in the case, aligning the key with the keyway in the gear.
  2.  
  3. Install the nuts and washers attaching the pump and draw the pump into position. Do not tighten the fasteners completely, at this time.
  4.  
  5. Install the bolt attaching the pump to the rear support. Install the washer and nut attaching the pump to the drive gear. Torque the nut to 50 ft. lbs.
  6.  
  7. Install the pump drive gear cover and new gasket.
  8.  
  9. Adjust the injection timing as described above.
  10.  
  11. Connect all other components in the reverse of their removal order. Bleed the system through the priming pump, as described above. Run the engine and check for leaks.
  12.  

INJECTION TIMING



See Figures 4, 5 and 6

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Fig. Fig. 4: Installing the injection pump timing gauge



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Fig. Fig. 5: Aligning the timing mark



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Fig. Fig. 6: Moving the crankshaft pulley timing mark

A static timing gauge adapter and metric dial indicator are necessary for this procedure.

  1. Disconnect the battery ground cables.
  2.  
  3. Remove the distributor head plug bolt from the injection pump.
  4.  
  5. Install the timing gauge adapter and metric dial indicator so that the indicator pointer is in contact with the injection pump plunger and the gauge reads 2.0mm (0.0787 in.).
  6.  
  7. Align the 2º ATDC mark on the crankshaft pulley with the indicator on the timing gear case cover.
  8.  
  9. Slowly turn the engine counterclockwise until the dial indicator pointer stops moving (approximately 30-50º pulley travel).
  10.  
  11. Adjust the dial indicator to 0. Confirm that the dial indicator does not move from 0, by rotating the crankshaft slightly from right to left.
  12.  
  13. Turn the crankshaft clockwise until the timing mark is once again aligned with the cover pointer. The dial indicator should read 1mm +- 0.02mm (0.0394 in. +- 0.00079 in.). If not, proceed to Step 8.
  14.  
  15. Loosen the injection pump mounting nuts and bolts.
  16.  
  17. Rotate the pump counterclockwise past the correct timing position, then clockwise until timing is correct.
  18.  
  19. Repeat the timing check to make sure the adjustment is correct.
  20.  

 
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