0341285 JOHNSON SCREW, Cover

This is an on engine test that is used to determine if the Fuel Ratio Control (FRC) is set properly. If the FRC is set properly, no additional procedures will be required. If the FRC is set incorrectly, the governor must be removed and the governor must be adjusted. The governor is adjusted according to the procedures that are covered in Service Manual, SENR6454, "3114, 3116, and 3126 Engine Governors".To determine the Fuel Ratio Control setting, complete the following steps:
Install the 128-8822 Fuel System and Governor Tool Gp. Refer to Systems Operation Testing and Adjusting, "Unit Injector - Adjust" for the instructions on the installation of the 128-8822 Fuel System and Governor Tool Gp. Note: A digital indicator is recommended for the following test procedures.
Illustration 1 g00700472
Typical Governor
(1) Fuel Ratio Control (FRC)
(2) Port (boost line)
(3) Low idle screw
(4) High idle screw
Disconnect the boost line from port (2) for the boost line. Apply air to the port, once the boost line is disconnected. Note: A regulated air supply of 140 to 210 kPa (20 to 30 psi) MUST be used in order to avoid damage to the FRC.
While the engine is operating at low idle, quickly actuate the throttle to the high idle position.
Record the maximum reading that is observed on the digital indicator as the engine's speed increases to high idle. This reading is the dynamic maximum fuel setting value. Repeat the procedure several times and average the values. Note: Static engine rack values and dynamic engine rack values may vary due to the following items: the method of fuel setting calibration and the differences in governor settings. When the "on engine" fuel setting is adjusted statically, a calibration pin is used as the reference dimension to the governor. This pin is used on all engines regardless of governor settings. This common calibration point and the different settings in the governor will cause the static engine rack values and dynamic engine rack values to differ. This difference depends on the part number of the governor since the load stop setting can have an adjustment between 9.0 mm (0.35 inch) and 10.4 mm (0.41 inch). When the pin is in place, the governor travel is restricted. When the pin is removed and the engine is running, the governor is unrestricted. This procedure allows a higher dynamic engine rack value. this value is higher than one that can be obtained statically with the calibration pin in place.
Disconnect the air pressure from the FRC and vent the FRC to the atmosphere.
While the engine is operating at low idle, quickly actuate the throttle to the high idle position.
Record the maximum reading that is observed on the digital indicator as the engine's speed increases to high idle. This reading is the dynamic maximum fuel setting value. Repeat the procedure several times and average the values.
Subtract the FRC setting value that was obtained in Step 7 from the dynamic maximum fuel setting value that was obtained in Step 4. This difference is the "on engine" FRC delta.
Use the following calculation in order to determine the governor's FRC delta. Subtract the specification for the FUEL RATIO CONTROL from the specification for the LOAD STOP. This difference is the governor's FRC delta. Note: Refer to Technical Marketing Information (TMI), "Governor Bench Performance Data" for the correct specifications for the FUEL RATIO CONTROL and the LOAD STOP.
If the on engine FRC delta is within .20 mm ( 0.008 inch) of the specifications for the governor's FRC delta, then the FRC is set properly.
If the on engine FRC delta is out of tolerance, the governor will need to be removed from the engine and the governor will need to be set to specifications. Use the 1U-7326 Governor Calibration Bench in order to set the governor. Note: Refer to Service Manual, SENR6454, "3114, 3116, and 3126 Engine Governors " for the instructions on the 1U-7326 Governor Calibration Bench.