GM Full-Size Trucks 1980-1987 Repair Guide

Fuel Injection Pump

Print

REMOVAL & INSTALLATION



See Figures 1, 2, 3 and 4

350 cu. in. Engine
  1. Remove the air cleaner.
  2.  
  3. Remove the filters and pipes from the valve covers and air crossover.
  4.  
  5. Remove the air crossover and cap and intake manifold with screened covers (tool J-26996-1).
  6.  
  7. Disconnect the throttle rod and return spring.
  8.  
  9. Remove the bellcrank.
  10.  
  11. Remove the throttle and transmission cables from the intake manifold brackets.
  12.  
  13. Disconnect the fuel lines from the filter and remove the filter.
  14.  
  15. Disconnect the fuel inlet line at the pump.
  16.  
  17. Remove the rear A/C compressor brace and remove the fuel line.
  18.  
  19. Disconnect the fuel return line from the injection pump.
  20.  
  21. Remove the clamps and pull the fuel return lines from each injection nozzle.
  22.  
  23. Using two wrenches, disconnect the high pressure lines at the nozzles.
  24.  
  25. Remove the three injection pump retaining nuts with tool J-26987 or its equivalent.
  26.  
  27. Remove the pump and cap all lines and nozzles.
  28.  

To install:
  1. Remove the protective caps.
  2.  
  3. Line up the offset tang on the pump driveshaft with the pump driven gear and install the pump.
  4.  
  5. Install, but do not tighten the pump retaining nuts.
  6.  
  7. Connect the high pressure lines at the nozzles.
  8.  
  9. Using two wrenches, torque the high pressure line nuts to 25 ft. lbs.
  10.  
  11. Connect the fuel return lines to the nozzles and pump.
  12.  
  13. Align the timing mark on the injection pump with the line on the timing mark adapter and torque the mounting nuts to 35 ft. lbs.
  14.  

A3/4 in. open end wrench on the boss at the front of the injection pump will aid in rotating the pump to align the marks.

  1. Adjust the throttle rod as follows:
    1. Remove the clip from the cruise control rod and remove the rod from the bellcrank.
    2.  
    3. Loosen the locknut on the throttle rod a few turns, then shorten the rod several turns.
    4.  
    5. Rotate the bellcrank to the full throttle stop, then lengthen the throttle rod until the injection pump lever contacts the injection pump full throttle stop, then release the bellcrank.
    6.  
    7. Tighten the throttle rod locknut.
    8.  

  2.  
  3. Install the fuel inlet line between the transfer pump and the filter.
  4.  
  5. Install the rear A/C compressor brace.
  6.  
  7. Install the bellcrank and clip.
  8.  
  9. Connect the throttle rod and return spring.
  10.  
  11. Adjust the transmission cable:
    1. Push the snap-lock to the disengaged position.
    2.  
    3. Rotate the injection pump lever to the full throttle stop and hold it there.
    4.  
    5. Push in the snap-lock until it is flush.
    6.  
    7. Release the injection pump lever.
    8.  

  12.  
  13. Start the engine and check for fuel leaks.
  14.  
  15. Remove the screened covers and install the air crossover.
  16.  
  17. Install the tubes in the air flow control valve in the air crossover and install the ventilation filters in the valve covers.
  18.  
  19. Install the air cleaner.
  20.  
  21. Start the engine and allow it to run for two minutes. Stop the engine, let it stand for two minutes, then restart. This permits the air to bleed off within the pump.
  22.  



Click image to see an enlarged view

Fig. Fig. 1: 350 diesel injection pump



Click image to see an enlarged view

Fig. Fig. 2: Offset on 350 diesel injection pump driven gear



Click image to see an enlarged view

Fig. Fig. 3: 350 diesel throttle assembly



Click image to see an enlarged view

Fig. Fig. 4: 379 diesel injection pump mounting

379 cu. in. Engine
  1. Disconnect both batteries.
  2.  
  3. Remove the fan and fan shroud.
  4.  
  5. Remove the intake manifold as described in Engine & Engine Overhaul .
  6.  
  7. Remove the fuel lines as described in this Section.
  8.  
  9. Disconnect the alternator cable at the injection pump, and the detent cable (see illustration) where applicable.
  10.  
  11. Tag and disconnect the necessary wires and hoses at the injection pump.
  12.  
  13. Disconnect the fuel return line at the top of the injection pump.
  14.  
  15. Disconnect the fuel feed line at the injection pump.
  16.  
  17. Remove the air conditioning hose retainer bracket if equipped with A/C.
  18.  
  19. Remove the oil fill tube, including the crankcase depression valve vent hose assembly.
  20.  
  21. Remove the grommet.
  22.  
  23. Scribe or paint a match mark on the front cover and on the injection pump flange.
  24.  
  25. The crankshaft must be rotated in order to gain access to the injection pump drive gear bolts through the oil filler neck hole.
  26.  
  27. Remove the injection pump-to-front cover attaching nuts. Remove the pump and cap all open lines and nozzles.
  28.  

To install:
  1. Replace the gasket. This is important.
  2.  
  3. Align the locating pin on the pump hub with the slot in the injection pump driven gear. At the same time, align the timing marks.
  4.  
  5. Attach the injection pump to the front cover, aligning the timing marks before tightening the nuts to 30 ft. lbs. (40 Nm).
  6.  
  7. Install the drive gear to injection pump bolts, tightening the bolts to 20 ft. lbs. (25 Nm)
  8.  
  9. Install the grommet.
  10.  
  11. Install the oil fill tube, including the crankcase depression valve vent hose assembly.
  12.  
  13. Reattach the air conditioning hose retainer bracket if equipped with A/C.
  14.  
  15. Reconnect the fuel feed line at the injection pump. Tighten the fitting to 20 ft. lbs. (25 Nm).
  16.  
  17. Reconnect the fuel return line at the top of the injection pump.
  18.  
  19. Reconnect the wires and hoses at the injection pump.
  20.  
  21. Reconnect the alternator cable at the injection pump, and the detent cable (see illustration) where applicable.
  22.  
  23. Reinstall the fuel lines as described in this Section.
  24.  
  25. Install the intake manifold following the instructions in Engine & Engine Overhaul .
  26.  
  27. Install the fan and fan shroud.
  28.  
  29. Reconnect both batteries.
  30.  
  31. Start the engine and check for leaks.
  32.  

INJECTION TIMING CHECK



For the engine to be properly timed, the marks on the top of the engine front cover and the injection pump flange must be aligned. The engine must be off when the timing is reset. On 49 states models, align the scribe marks. On California models, align the half-circles.



Click image to see an enlarged view

Fig. Fig. 5: 350 diesel timing marks and injection pump lines

INJECTION TIMING ADJUSTMENT



See Figure 5

350 (5.7L) Engine
  1. The engine must be off for resetting the timing.
  2.  
  3. Loosen the three pump retaining nuts with tool J-26987, an injection pump intake manifold wrench, or its equivalent.
  4.  
  5. Align the mark on the injection pump with the marks on the adapter and tighten the nuts. On 350 (5.7 liter) diesels, torque the nuts to 35 ft. lbs. (47 Nm). Use a 3 /4 in. open-end wrench on the boss at the front of the injection pump to aid in rotating the pump to align the marks.
  6.  
  7. Adjust the throttle rod:
    1. Remove the clip from the cruise control rod and remove the rod from the bellcrank.
    2.  
    3. Loosen the locknut on the throttle rod a few turns, then shorten the rod several turns.
    4.  
    5. Rotate the bellcrank to the full throttle stop, then lengthen the throttle rod until the injection pump lever contacts the injection pump full throttle stop, then release the bellcrank.
    6.  
    7. Tighten the throttle rod locknut.
    8.  

  8.  

379 (6.2L) Engine
  1. The engine must be off for resetting the timing.
  2.  
  3. Loosen the three pump retaining nuts.
  4.  
  5. Align the mark on the injection pump with the marks on the adapter and tighten the nuts. Torque the pump nuts to 30 ft. lbs. (40 Nm). Use a 3 /4 in. open-end wrench on the boss at the front of the injection pump to aid in rotating the pump to align the marks.
  6.  

 
label.common.footer.alt.autozoneLogo