GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Injection Pump

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REMOVAL & INSTALLATION



See Figure 1

  1. Disconnect the negative (-) battery cable. 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 intake manifold with screened covers (tool J-26996-10).
  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. On 1983 and later models, remove the crankcase depression regulator valve.
  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. If equipped with a fuel line heater, remove the fasteners retaining the line and heater.
  18.  
  19. Disconnect the fuel return line from the injection pump.
  20.  

On 1982 and earlier models:
  1. Remove the clamps and pull the fuel return lines from each injection nozzle.
  2.  
  3. Using two wrenches to avoid putting torque on the nozzles, disconnect the high pressure lines at the nozzles.
  4.  

On 1983 and later models:
  1. Disconnect the injection line clamps.
  2.  
  3. Disconnect the injection lines at the pump and cap all openings. Then, reposition the lines slightly as necessary to gain enough clearance for pump removal.
  4.  
  5. Remove the three injection pump retaining nuts with tool J-26987 or its equivalent.
  6.  
  7. Remove the pump. Immediately cap all lines and nozzles. Discard the pump-to-adapter O-ring.
  8.  



Click image to see an enlarged view

Fig. Fig. 1: Diesel injection pump

To install:
  1. Remove the protective caps.
  2.  
  3. Line up the offset tang on the pump driveshaft with the pump driven gar and install the pump.
  4.  
  5. Install, but do not tighten the pump retaining nuts.
  6.  
  7. On 1982 and earlier models, connect the high pressure lines at the nozzles.
  8.  
  9. Using two wrenches, torque the high pressure line nuts to 25 ft. lbs. (34 Nm) on 1982 and earlier models.
  10.  
  11. Connect the fuel return lines to the nozzles and pump on 1982 and earlier models.
  12.  
  13. Align the timing mark on the injection pump with the line on the timing mark adaptor and torque the mounting nuts to 35 ft. lbs. (47 Nm) on models up to 1979 and 18 ft. lbs. (25 Nm) on models built in 1980 and later years.
  14.  

A3/4in. (19mm) open end wrench on the boss at the front of the injection pump will aid in rotating the pump to align the marks.

On 1983 and later models, remove the protective caps and connect the injection lines to the pump, torquing to 25 ft. lbs. (34 Nm). Then connect the injection lines to the pump, torquing to 25 ft. lbs. (34 Nm). Connect injection line clamps on these models. Also on these models only, install the fuel filter and bracket, tighten fuel line fittings, and install the fuel line heater clamps (where equipped). Install the crankcase depression regulator.

  1. 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.  

  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. On 1982 and earlier models, use this method to bleed air out of the injection pump: Start the engine and allow it to run for two minutes; stop the engine and allow it to stand for two minutes; then restart the engine.
  22.  
  23. On 1983 and later models, an extremely precise timing meter is used by professional mechanics to set injection timing by replacing the glow plug of No. 3 cylinder with an electronic probe. Since the probe sets timing by measuring crankshaft position when the injected fuel actually ignites, it eliminates a great number of possible kinds of error. Proper injection timing maximizes fuel economy and minimizes all engine stresses. Even though a precise alignment of the injection pump ensures reasonably accurate timing, you should have your timing set professionally to ensure best results.
  24.  

Also, if you have disturbed the vacuum regulator valve position or replaced the injection pump, this valve should be adjusted professionally. The procedure is very simple, but requires an expensive special tool.

  1. Connect the negative battery cable.
  2.  
  3. On all models, adjust the idle speed as described later in this section.
  4.  
  5. Start the engine and check for fuel leaks and proper operation.
  6.  

ADJUSTMENTS



Slow Idle Speed
  1. Apply the parking brake, put the transmission in Park and block the drive wheels. Check the throttle linkage adjustment and adjust it if necessary.
  2.  
  3. Start the engine and allow it to run until it is warm (about 15 minutes). Then, shut the engine off and remove the air cleaner.
  4.  
  5. Clean off the front cover rpm counter (the probe holder) and the rim of the crankshaft balancer. Install the magnetic pickup probe of the magnetic pickup tachometer fully into the rpm counter. Connect the battery leads (red to positive, black to negative).
  6.  
  7. Disconnect the two lead connector at the generator.
  8.  
  9. Turn off all electrical accessories.
  10.  


CAUTION
Block all wheels and apply the emergency brake before placing the transmission in DRIVE. Personal injury may result if this procedure is not followed!

  1. Start the engine and place the transmission in Drive. Read the slow idle speed, making sure the steering wheel and brake pedal are not touched. Reset the idle speed by turning the screw if it does not agree with the figure on the engine compartment sticker. If the sticker is not present, adjust the idle speed to 600 rpm in DRIVE. Be sure to put the transmission back in Park, reconnect the generator lead, and reinstall the air cleaner when you have finished.
  2.  

Fast Idle Solenoid
MODELS TO 1981

CAUTION
Block all wheels and apply the emergency brake before placing the transmission in DRIVE. Personal injury may result if this procedure is not followed!

  1. Set the parking brake and block the drive wheels.
  2.  
  3. Run the engine to normal operating temperature.
  4.  
  5. Place the transmission in DRIVE , disconnect the compressor clutch wire and turn the A/C On. On vehicles without A/C, disconnect the solenoid wire, and connect jumper wires to the solenoid terminals. Ground one of the wires and connect the other to a 12 volt power source to activate the solenoid.
  6.  
  7. Adjust the fast idle solenoid plunger to obtain 650 rpm.
  8.  

MODELS 1982 AND LATER
  1. Unplug the connector from the EGR-TVS and install a jumper between the connector terminals WITHOUT ALLOWING THE JUMPER TO TOUCH GROUND!
  2.  
  3. Apply the parking brake, put the transmission in Park and block the drive wheels. Check the throttle linkage adjustment and adjust it if necessary.
  4.  
  5. Start the engine and allow it to run until it is warm (about 15 minutes). Then, shut the engine off and remove the air cleaner.
  6.  
  7. Clean off the front cover rpm counter (the probe holder) and the rim of the crankshaft balancer. Install the magnetic pickup probe of the magnetic pickup tachometer fully into the rpm counter. Connect the battery leads (red to positive, black to negative).
  8.  
  9. Disconnect the two lead connector at the generator.
  10.  
  11. Turn off all electrical accessories.
  12.  


CAUTION
Block all wheels and apply the emergency brake before placing the transmission in DRIVE. Personal injury may result if this procedure is not followed!

  1. Place the transmission in Drive. Check the fast idle speed by reading the magnetic pickup tachometer and compare the reading to the fast idle solenoid speed specified on the engine compartment sticker. If the sticker is not present, adjust the fast idle to 750 rpm in DRIVE. Change the setting by turning the solenoid plunger at the flats.
  2.  
  3. Remove the jumper and reconnect the connector. Stop the engine, and then reconnect the generator connector.
  4.  
  5. Remove the tachometer. If the vehicle has cruise control, adjust the servo throttle rod to minimize the slack. Then, install the clip in the first free hole closest to the bellcrank or throttle lever but still within the bail on the servo. Install the air cleaner (make sure to reconnect the EGR hose).
  6.  

Cruise Control Servo Relay Rod
  1. Turn the ignition switch to Off.
  2.  
  3. Adjust the rod to minimum slack then put the clip in the first free hole closest to the bellcrank, but within the servo bail.
  4.  

INJECTION TIMING



See Figure 2

For the engine to be properly timed, the lines on the top of the injection pump adapter and the flange of the injection pump must be aligned.

  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 timing marks and torque the pump retaining nuts to 35 ft. lbs. (47 Nm) on 1979 and earlier models and 18 ft. lbs. (25 Nm) on 1980 and later models. On 1982 and later models, timing should be precisely adjusted using the special timing meter discussed in the procedure for injection pump removal and installation.
  6.  

The use of a3/4in. (19mm) open end wrench on the boss at the front of the pump will aid in rotating the pump to align the marks.

  1. Adjust the throttle rod.
  2.  



Click image to see an enlarged view

Fig. Fig. 2: Diesel timing marks

 
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