3306C Truck Engine Caterpillar

Fuel Air Ratio Control and Governor Check

Note: The governor seals do not need to be cut or removed for the procedures that follow. For more information on the tooling, watch Video Tape, SEVV9173 and Special Instruction, SEHS8463. This Special Instruction is available only on microfiche.

1. Install the rack position indicator in order to measure the movement of the fuel rack.

2. Turn the ignition key to "ON". This activates the shutoff solenoid. DO NOT START THE ENGINE AT THIS TIME.

3. Move the governor control linkage to the full FUEL-ON position. Hold the governor control linkage in this position, or fasten the control linkage in this position.

4. Install the 6V-4186 Fuel Pump Timing Pin in the hole for the rack's zeroing pin inside the pump housing.

5. With the governor control lever in the full FUEL-OFF position, use a 1N-9954 Lever to slowly move the manual shutoff shaft, if equipped. Move this manual shutoff shaft to the FUEL-OFF position. This moves in a counterclockwise direction.

   Make sure that the 6V-4186 Fuel Pump Timing Pin drops into the slot in the fuel rack. Also, make sure that the pin engages with the slot in the fuel rack.

6. Release the manual shutoff shaft and the 8T-1000 Electronic Position Indicator. Press the zero button.

7. Remove the 6V-4186 Fuel Pump Timing Pin, and watch the movement.

   The electronic position indicator should display a positive reading in the "FUEL ON" direction.

   Note: If no movement occurs, repeat Steps 4, 5, and 6.

8. Release the governor control shaft and the governor control linkage.

9. Remove the air line from the engine. Put plugs over the opening. This keeps dirt out of the system.

10. Start the engine, and allow the engine to run for a minimum of five minutes. This warm-up time is required for the following reasons:
    • The governor gets enough time to attain normal operating temperature.

    • The engine gets enough time to attain normal operating temperature.

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Personal injury can result from rotating and moving parts. Moving fan blades and moving parts will throw or cut any object or tool that falls or is pushed into them. Ensure that no one is working on, underneath or close to the machine before starting the engine. Ensure the area is free of personnel.

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Illustration 1	g00320303
FT-1906 Air Test Kit (1) BL-6557 Connector (2) 5P-4405 Air Brake Connector (two) (3) 5P-6011 Tube (4) 5P-4476 Air Brake Connector (5) 6K-5741 Valve (6) 5P-4459 Air Brake Elbow (7) 7B-0192 Cross (8) 3B-6768 Bushing (9) 6V-7775 Air Pressure Gauge (10) 3B-3169 Hose Assembly (11) 6V-6757 Pipe Elbow (12) Flexible tubing with an ID of 6.35 mm (0.2500 inch) and a length of 1.2 m (4 ft) (13) Air pressure bulb Baumamometer

11. Check the leakdown rate of the fuel air ratio control with the engine at low idle. Follow these steps:

    1. Connect the following items to the fitting that was left from the removal of the air line:
       • Pressure gauge

       • Shutoff valve

       • Pressure regulator

       • Air supply

    2. Apply 70 kPa (10 psi) of air pressure to the fuel air ratio control.

    3. Turn off the shutoff valve, and check the leakdown rate.

       Note: A leakdown rate of 20 kPa (3 psi) within 30 seconds is acceptable.

    4. If leakage is more than 20 kPa (3 psi) within 30 seconds, the fuel air ratio control needs to be repaired before Steps 14 through 16 are completed.

    5. Apply 70 kPa (10 psi) of air pressure on the fuel air ratio control for Step 12.

       Note: Step 11 also activates the fuel air ratio control for Step 12.

12. While the engine is operating at low idle, rapidly move the governor control shaft to the FUEL-ON position. Then, read the measurement on the 8T-1000 Electronic Position Indicator .

13. Press the "MAX" on the position indicator and then read the dynamic fuel air ratio control setting. Record the reading, and repeat this step several times.

    Note: The fuel air ratio control is activated, and the maximum reading is the dynamic full torque setting of the engine. This setting is 0.5 mm (0.02 inch) greater than the static full torque setting. The static full torque setting appears on the Engine Information Plate for later engines. This information can also be found in the TMI.

    Note: The fuel air ratio control activates at start-up for engines with a fuel air ratio control that is out of adjustment. At this time, the reading of the 8T-1000 Electronic Position Indicator can be the dynamic full torque setting for Step 17.

14. Release all the air pressure from the fuel air ratio control.

15. While the engine is operating at 900 rpm, rapidly move the governor control shaft to the FUEL-ON position. Then, read the measurement on the 8T-1000 Electronic Position Indicator .

16. Press the "MAX" on the indicator, and then read the dynamic fuel air ratio control setting. Record the reading, and repeat this step several times.

    Note: An adjustment is not needed if the dynamic fuel air ratio setting is within 0.25 mm (0.0098 inch) of the specifications in either of the following references:

    • The Engine Information Plate for later engines

    • TMI

    For adjustment of the control, see the "Fuel Air Ratio Control Adjustment".

17. Observe these steps to check the inlet air pressure for full torque rack travel:

    1. Connect the following items to the fitting that was left from the removal of the air line:
       • Pressure gauge

       • Pressure regulator

       • Air supply

    2. Apply 25 kPa (4 psi) of air pressure to the fuel air ratio control.

    3. Run the engine at 900 rpm. Rapidly move the governor control shaft to the full FUEL-ON position. Record the maximum reading on the indicator.

    4. Repeat this process several times. With each repetition, increase the air pressure by 5 kPa (0.5 psi).

    5. Record the first air pressure setting that registers the full torque rack travel.

       Note: Remember that the full torque rack travel was calculated in Step 13.

    6. This is the inlet air pressure that moves the fuel air ratio control out of the rack control position. This pressure provides the dynamic full torque rack travel.

Fuel Air Ratio Control Adjustment

Note: Before the governor seals are removed or the governor seals are severed, check the "Fuel Air Ratio Control and Governor Check" in order to make sure that an adjustment is needed.

1. See either of the following references for the correct specification of the dynamic fuel air ratio setting before you make an adjustment:
   • The Engine Information Plate for later engines

   • TMI

2. Install the zero rack position indicator group, and zero the rack position indicator.

   Note: See the "Fuel Air Ratio Control and Governor Check" for more information regarding this procedure.

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Illustration 2	g00320407
Earlier Fuel Air Ratio Control (1) Nut (valve extension). (2) Retainer. (3) Stop. (4) Nut. (5) Valve extension.

3. Remove the cover from the fuel air ratio control valve.

   Note: For earlier engines, the completion of Step 4 is necessary to make sure that stop (3) does not contact retainer (2). Later engines do not contain stop (3) and nut (4). Do not add these parts when you repair the fuel air ratio control.

4. Loosen nut (4), and turn stop (3) clockwise until stop (3) contacts the shoulder on retainer (2). Next, turn the stop (3) counterclockwise for two complete turns. Tighten nut (4) .

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Illustration 3	g00367447
Later Fuel Air Ratio Control (1) Nut (valve extension). (5) Valve extension.

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Personal injury can result from rotating and moving parts. Moving fan blades and moving parts will throw or cut any object or tool that falls or is pushed into them. Ensure that no one is working on, underneath or close to the machine before starting the engine. Ensure the area is free of personnel.

5. Start the engine, and allow the engine to run for a minimum of five minutes. This warm-up time is required for the following reasons:
   • The governor gets enough time to attain normal operating temperature.

   • The engine gets enough time to attain normal operating temperature.

6. Activate the fuel air ratio control by pushing in on valve extension (5) .

7. Hold retainer (2) in position, and loosen nut (1). This prevents the fuel air ratio control diaphragm from turning when you loosen nut (1) .

   Note: Use the same procedure to tighten this nut.

8. Turn valve extension (5) in order to attain the correct setting. A clockwise movement provides a more positive setting.

   Note: A counterclockwise movement provides a more negative setting.

   Several adjustments of valve extension (5) may be needed to meet the specifications.

9. After each adjustment is made, check the dynamic fuel air ratio control setting:

   1. Operate the engine at 900 rpm, and rapidly move the governor control shaft to the FUEL-ON position.

   2. Carefully read the dial indicator. This reading will only be at a maximum for a moment. Record the reading on the indicator.

      Note: If the correct dynamic fuel air ratio control setting can NOT be made with this adjustment, check the internal governor linkage for another possible adjustment. Check the fuel air ratio control linkage for repair and for replacement.

10. After the correct adjustment has been made and while retainer (2) is held in position, tighten nut (1). Also, check the fuel air ratio control setting again.

11. Install the gasket and the cover on the fuel air ratio control. Then, install the cover to a torque of 9 ± 3 N·m (7 ± 2 lb ft).

12. Apply 70 kPa (10 psi) of air pressure to the fuel air ratio control at the fitting. This will fully extend the fuel air ratio control so the dynamic full torque can be attained.

13. Check the dynamic full torque setting:

    1. Operate the engine at 900 rpm.

    2. Rapidly move the governor control shaft to the full FUEL-ON position.

    3. Read the maximum measurement that is displayed on the dial indicator.

       Note: If the dynamic full torque setting can NOT be reached, the fuel air ratio control may need to be repaired or replaced.

14. Stop the engine.

15. Install the wire and the seal onto the fuel air ratio control.

16. Install the air line onto the engine.

17. Remove the tooling for the rack position indicator.