carburetor adjustments

Special Instruction Installation and Initial Start-Up Procedure for G3500 Engines{1000}

Installation and Initial Start-Up Procedure for G3500 Engines{1000} SMCS - 1000

Engine: G3508 (S/N: 4WD1-UP; 9TG1-UP; 2TJ1-UP; 9AW1-UP; CTN1-UP) G3512 (S/N: 5JD1-UP; 7NJ1-UP; 6JW1-UP; CTM1-UP) G3516 (S/N: 8LD1-UP; 4EK1-UP; 8PW1-UP; CTL1-UP) G3524 (S/N: 7SZ1-UP; 5ZZ1-UP) G3532 (S/N: 8BZ1-UP; 8JZ1-UP)

Introduction Do not perform any procedure in this Special Instruction until you read this information and you understand this information.

This Special Instruction includes the initial start-up procedures for G3500 engines. The correct initial start-up of the engine is essential for the following reasons:

Engine service life

Fuel economy

Acceptable emissions

Service technicians should have a thorough understanding of the relationship between the fuel system and the ignition system. The technician must also be familiar with the literature that is listed in the ""References" " section.

References Engine Service Manual, SENR6415

Industrial Engine Performance, LEBQ6117

Engine Performance, LEBQ6169

Systems Operation Testing and Adjusting, SENR6412

Troubleshooting, SENR6413

Specifications, SENR6417 and Specifications, SENR6411

Operation and Maintenance, SEBU6711 and Operation and Maintenance, SEBU7551

Media Number -SEHS9769-05 Publication Date -13/03/2007 Date Updated -13/03/2007

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07/10/2008https://sis.cat.com/sisweb/sisweb/techdoc/content.jsp?calledpage=/sisweb/sisweb/med...

Required Information

Ignition Timing

A complete fuel analysis must be conducted prior to putting the engine into service. Obtain a fuel analysis in order to determine the energy content and calculate the methane number. The methane number indicates the ability of the fuel to be ignited. The methane number is determined when you input the data from the fuel analysis into the Methane Number Program, LEKQ6378. Use the methane number and the Engine Performance, "Fuel Usage Guide" in order to determine the ignition timing.

Obtain several samples of fuel if the quality is expected to change. If the methane number will vary during engine operation, use the lowest expected value in order to determine ignition timing.

Maximum Load

Refer to the Engine Performance, LEBQ6169 in order to determine the engine power level for the altitude, the temperature and the methane number. Use the information in the Engine Performance, LEBQ6169 in order to determine the maximum engine load. The desired engine load must not exceed the maximum engine load.

Inlet Manifold Pressure at Full Load

For generator set applications, use the generator power output to determine the engine load. For other applications, use the inlet manifold pressure to estimate the engine load. The inlet manifold pressure may be used if the engine timing and the exhaust oxygen are set properly. The Engine Performance, LEBQ6169 provides inlet manifold pressures for specific setting for timing and emissions. This information may be used to estimate the output power of the engine. If the engine power is derated, interpolate the desired inlet manifold pressure between the 100 percent and the 75

Table 1

Tools Needed

Part Number Description

7X-1400 Electronic Tool Gp (1)

NEXG4511 Service Program Module For Gas Engines (1)

140-2304 Governor Electronic Control Programmer (2)

8T-0452 Manometer Gauge

156-1060 Emissions Analyzer Gp

1P-2385 Protractor

6V-7070 Digital Multimeter ( 1 ) Refer to Using the DDT NEXG4511 Industrial Application Function Service Program Module, SEHS8806 for more

information on using the digital diagnostic tool. Also refer to Service Program Module For Spark Ignited Engines, NEXG4511. You must have the chip in order for the 7X-1400 Electronic Tool Group to work.

( 2 ) This is for engines that are equipped with 701A Woodward governors.



percent load ratings.

Exhaust Oxygen Level

The 156-1060 Emissions Analyzer or another emissions analyzer is required in order to properly set up a gas engine. The Engine Performance, LEBQ6169 gives the levels of oxygen for engine loads of 50 percent, for 75 percent, and for 100 percent. Set up the engine in accordance with the Engine Performance, LEBQ6169 at the desired full load with the data that was taken at 100 percent load. Do not exceed the maximum load.

Carburetor Adjustments

The carburetor and the gas pressure regulator require adjustment when the engine is installed. The initial factory settings are based on the following conditions:

An ambient temperature of 25 °C (77 °F)

A barometric pressure of 100 kPa (29.92 in Hg)

The use of a natural gas pipeline with a Low Heating Value of 33.74 kJ/L (905 BTU/cu ft)

The factory ratings comply with SAE J1349 Standards. An engine with a low pressure fuel system that does not use natural gas may be shipped with optional orifices and valves. The optional orifices and the valves should be ordered with the engine. Contact your Caterpillar dealer for more information.

Gas Pressure Regulator

The gas pressure regulator requires adjustment when the engine is installed. Use only Caterpillar approved regulators in order to avoid problems with performance. A balance line for the regulator is required in all gas engines. This line compensates for changes in boost pressure or in air filter restriction. Refer to the Systems Operation Testing and Adjusting, SENR6412 for details.

Note: The supply line to the gas pressure regulator must be of adequate diameter in order to provide constant pressure to the regulator from idle to full load. Do not use supply lines that are smaller than the inlet to the pressure regulator.

Connect Gauges and Instruments Caterpillar Electronic Service Tools are designed to help the service technician perform the following procedures:

Obtain data.

Diagnose problems.

Read parameters.

Program parameters.

Calibrate sensors.



The tools that are listed in Table 2 are required in order to enable a service technician to perform the procedures.

There are two electronic service tools that can be used on the engine. The tools are the Caterpillar Electronic Technician (ET) and the Digital Diagnostic Tool (DDT). The tools can be connected at various locations. The locations depend on the application and the optional equipment. Refer to Illustration 1 for the locations.

Table 2

Service Tools

Pt. No. Description Functions

8T-8726

Adapter Cable As

This breakout harness is for use between the jacks and the plugs of the sensors.

151-6320

Wire Removal Tool

This tool is used for the removal of pins and sockets from Deutsch connectors and from AMP connectors.

1U-5804 Crimp Tool This tool is used for work with CE electrical connectors.

6V-7070

Digital Multimeter

The multimeter is used for the testing and the adjusting of electronic circuits.

7X-1710

Multimeter Probes

The probes are used with the multimeter to measure voltage in wiring harnesses without disconnecting the harnesses.

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Illustration 1 g

Locations for the connection of the electronic service tools

(1) Engine mounted terminal box

(2) Engine Supervisory System



Caterpillar Electronic Technician (ET)

The tools that are listed in Table 3 are required in order to use Cat ET.

Note: For more information regarding the use of Cat ET and of the PC requirements for Cat ET, refer to the documentation that accompanies your Cat ET software.

The Cat ET is designed to run on a personal computer. Cat ET can display the following information:

Parameters

Diagnostic codes

Event codes

Engine configuration

Status of the monitoring system

Cat ET can perform the following functions:

Diagnostic tests

(3) Remote Control Panel (Status)

(4) Air/Fuel Ratio Control (CSA)

Table 3

Service Tools

Pt. No. Description Functions

N/A Personal Computer (PC) The PC is required for the use of Cat ET.

"JERD2124" Software

Single user license for Caterpillar Electronic Technician (ET) Use the most recent version of the software.

"JERD2129" Software Data subscription for all engines

171-4400 (1)

Communication Adapter Gp

This group provides the communication between the PC and the engine.

7X-1414 Data Link Cable As This cable connects the communication adapter to the service tool connector.

237-7547 Adapter Cable As This cable connects to the USB port on computers that are not equipped with a serial port.

( 1 ) The 7X-1700 Communication Adapter Gp may also be used.



Sensor calibration

Flash downloading

Set parameters

Connecting Cat ET with the 171-4401 Communication Adapter II

The engine's power supply provides the communication adapter with 24 VDC. Use the following procedure to connect Cat ET and the communication adapter to the engine.

1. Set the engine control to the OFF/RESET mode.

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Illustration 2 g01034079

Connecting Cat ET

(1) 7X-1414 Data Link Cable

(2) 207-6845 Adapter Cable

(3) 171-4401 Communication Adapter As

(4) 196-0055 Serial Cable or the 160-0141 Serial Cable



Note: Items (2), (3), and (4) are part of the 171-4400 Communication Adapter Gp .

2. Connect cable (4) to the RS232 serial port of PC (5) .

Note: If your PC is not equipped with a serial port, use the 237-7547 Adapter Cable As in order to connect to the USB port. Connect one end of the adapter to the end of cable (4). Connect the other end of the adapter to a USB port on the PC.

3. Connect cable (4) to communication adapter (3) .

4. Connect cable (2) to communication adapter (3) .

5. Connect cable (2) to cable (1) .

6. Connect cable (1) to the service tool connector.

7. Set the engine control to the STOP mode. The engine should be OFF. If Cat ET and the communication adapter do not communicate with the ECM, refer to Troubleshooting, SENR6413.

7X-1400 Electronic Tool Group

The Digital Diagnostic Tool (DDT) is used to program customer specified parameters such as information on the status of the engine. The DDT also reads the diagnostic codes and the DDT is used to perform timing calibrations.

Note: The Service Program Module For Gas Engines, NEXG4511 must be installed on the DDT.

Water Manometer

(5) PC

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Illustration 3 g00569592Low pressure fuel system

(1) Plug for the inlet of the gas line

(2) Plug in the adapter of the balance line

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The water manometer or the differential pressure gauge is not required for the Deltec mixer systems with zero pressure regulators. Two manometers are required for low pressure gas fuel systems with two Impco carburetors. One manometer is required for high pressure gas fuel systems with two Impco carburetors.

1. Turn the main gas valve OFF.

2. Remove the plug (1 or 4) from the gas supply line to the mixer.

3. For a high pressure system, remove plug (3) from the balance line. For a low pressure system, remove plug (2) from the air cleaner.

4. Connect a 1U-5470 Engine Pressure Group or a water manometer between the two pressure taps with the proper adapter fittings.

Note: Install a shutoff valve between the carburetor and the manometer for the high pressure systems. Close this valve when you start the engine or when you stop the engine.

Emissions Analyzer

Illustration 4 g00569790High pressure fuel system

(3) Plug for the air pressure manometer

(4) Gas supply pressure plug



Install the 156-1060 Emissions Analyzer in order to monitor the exhaust oxygen levels before the turbocharger. Remove the plug that is located in the exhaust inlet of the turbocharger, or in the exhaust elbow on naturally aspirated engines. Connect the 156-1060 Emissions Analyzer in accordance with the manufacturer's instructions.

Note: The measurements of the NOx and the CO may also be required.

Inlet Manifold

The inlet manifold pressure is measured below the throttle plate with a pressure gauge. The inlet manifold pressure is used to indicate the engine load.

Remove the plug from the gas supply line to the regulator and install a pressure gauge. This pressure gauge will monitor the supply pressure to the gas pressure regulator.

Carburetor Control Linkage (EG-3P Actuator)

Installation Procedure for the Linkage

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1. Disconnect the following parts: adjustable rod (5), adjustable rod (7) and adjustable rod (9) .

2. Set the length of adjustable rod (5) to dimension (X) in Table 4. The length of the rod is the measurement between the center of both rod ends.

3. Set the length of adjustable rod (9) to dimension (Y) in Table 4. The length of the rod is the measurement between the center of both rod ends.

4. Rotate governor actuator shaft (11) to the fully open position.

5. Hold governor actuator shaft (11) in the fully open position. Ensure that the governor actuator shaft is installed at an angle of 5 ± 5 degrees from the horizontal position.

Illustration 5 g(1) Carburetor throttle shaft

(2) Cross shaft

(3) Bearing assembly

(4) Carburetor throttle shaft lever

(5) Adjustable rod (upper link)

(6) Front cross shaft lever

(7) Adjustable rod (middle link)

(8) Idler lever

(9) Adjustable rod (lower link)

(10) Governor actuator shaft lever

(11) Governor actuator shaft

Table 4

Linkage Adjustment

Engine Dimension (X) Dimension (Y)

3516 4P-7316

179.8 ± 1.0 mm (7.08 ± 0.04 inch)

254.0 ± 1.0 mm (10.0 ± 0.04 inch)

3516 121-7548

222.5 ± 1.0 mm (8.76 ± 0.04 inch)

254.0 ± 1.0 mm (10.0 ± 0.04 inch)

3512 194.2 ± 1.0 mm (7.64 ± 0.04 inch)

254.0 ± 1.0 mm (10.0 ± 0.04 inch)

3508 194.2 ± 1.0 mm (7.64 ± 0.04 inch)

254.0 ± 1.0 mm (10.0 ± 0.04 inch)



6. Install adjustable rod (5) and adjustable rod (9) .

7. Rotate carburetor shaft (1) counterclockwise to the fully open position. The locking screw of the stop for the carburetor shaft will be against the dowel pin in the throttle body.

8. Hold carburetor shaft (1) and governor actuator shaft (11) in the fully open position. Install adjustable rod (7) so that the rod fits between the levers.

9. Rotate the linkage until the throttle is fully closed. Adjust the throttle stop screw until the screw contacts the dowel pin in the throttle body.

10. Check the linkage operation. The linkage must not bind at any position in the travel range. Hold the linkage in the fully closed position and release. The linkage should move to the fully open position. If the linkage does not move to the fully open position, lubricate the linkage and bearings.

Carburetor Control Linkage (3161 Governor)

Installation Procedure for the Linkage

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Illustration 6 g

(1) Carburetor throttle shaft

(2) Cross shaft



1. Disconnect adjustable rod (6) and adjustable rod (7) .

2. Set the length of adjustable rod (6) to dimension (X) in Table 5. The length of the rod is the measurement between the center of both rod ends.

3. Set the length of adjustable rod (7) to 404 mm (15.9 inch). The length of the rod is the measurement between the center of both rod ends.

4. Rotate governor control shaft (8) to the fully open position.

5. Hold governor control shaft (8) in the fully open position. Ensure that the governor control shaft is installed at an angle of 19 degrees from the vertical position.

6. Install adjustable rod (6) and adjustable rod (7) .

7. Rotate carburetor throttle shaft (1) counterclockwise to the fully open position. The locking screw of the stop for the carburetor throttle shaft will be against the dowel pin in the throttle body.

8. Rotate the linkage until the throttle is fully closed. Adjust the throttle stop screw until the screw contacts the dowel pin in the throttle body.

9. Check the linkage operation. The linkage must not bind at any position in the travel range. Hold the linkage in the fully closed position and release. The linkage should move to the fully open position. If the linkage does not move to the fully open position, lubricate the linkage and bearings.

Throttle Actuator and Flexible Coupling

(3) Bearing assembly

(4) Carburetor throttle shaft lever

(5) Rod end and nut

(6) Adjustable rod (upper link)

(7) Adjustable rod (lower link)

(8) Governor control shaft

Table 5

Linkage Adjustment

Engine Dimension (X)

G3508 194.2 ± 1 mm (7.6457 ± 0.04 inch) G3512

G3516 179.8 ± 1 mm (7.0787 ± 0.04 inch)



Installation Procedure for the Coupling

1. Rotate throttle shaft (6) to the closed position. Adjust the idle screw in order to contact the pin in the throttle body. Turn the idle screw an additional whole turn.

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Illustration 7 g01047869Throttle actuator and coupling

(1) Coupling

(2) Throttle body

(3) Actuator

(4) Coupling screw

(5) Coupling screw

(6) Throttle shaft

(7) Support for the actuator

(8) Actuator mounting bolts.



2. Loosely install actuator (3). The actuator is in the normally closed position.

3. Loosely install coupling (1). Check the alignment of the coupling.

Note: The maximum allowable angular misalignment is 1 degree. The maximum allowable amount of axial misalignment is 0.254 mm (0.010 inch).

4. Tighten the bolts for actuator (8). Recheck the alignment. If necessary, adjust the alignment.

5. Tighten screws (4) and (5) for the coupling to 2.25 ± .25 N·m (20 ± 2 lb in).

Carburetor Turn the load adjustment screw clockwise for a leaner fuel mixture. Turn the load adjustment screw counterclockwise for a richer fuel mixture.

Adjustment Procedure for the High Pressure Carburetor and the Low Pressure Carburetor

1. Ensure that the throttle linkage is correctly adjusted. Use a 1P-2385 Protractor to make this adjustment.

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2. Locate the load adjustment screw. Turn the screw clockwise until the screw is fully seated. Next, turn the screw 3.5 times in the counterclockwise direction.

Turn the load adjustment screw clockwise for a leaner fuel mixture. Turn the load adjustment screw counterclockwise for a richer fuel mixture.

Note: The adjusting screws for the carburetor must remain adjusted within 1/6 of a turn of each other on low pressure engines with two carburetors. If the carburetors are not adjusted correctly, one turbocharger is more likely to surge during large transient loads.

3. Set the gas line pressure into the gas pressure regulator. The proper range of the pressure settings follow:

Illustration 8 g00529416Low pressure Gas

(5) Load adjustment screw



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10 kPa (1.5 psi) to 35 kPa (5 psi) for engines with low pressure

210 kPa (30 psi) to 275 kPa (40 psi) for engines with low emissions, and high pressure

172 kPa (25 psi) for stoichiometric standard engines

Note: Authorization from the local utility may be required in order to obtain these supply pressures.

4. Before you start the engine, use the electronic service tool to program the ignition timing. Refer to ""Ignition Timing" " for details on determining the correct setting for the ignition timing. Program all other specified parameters. Refer to Troubleshooting, SENR6413.

5. Before you start the engine, be sure that the engine and the driven equipment are ready for operation by performing daily maintenance items. Refer to Operation and Maintenance Manual, SEBU6711.

6. Start the engine.

7. Refer to the ""Water Manometer" "section.

8. Run the engine at high idle speed with no load. Then adjust the gas pressure regulator in order to obtain a differential pressure of 10 cm (4 inch) of water. Adjust the regulator to the lowest pressure setting, if the regulator is unable to be adjusted to a pressure of 10 cm (4 inch) of water.

Adjust the differential pressure by removing the cap from the regulator. Turn the threaded disk with the 8T-5160 Gas Regulator Setting Tool . Turning the disk clockwise will increase differential pressure. Turning the disk counterclockwise will decrease the differential pressure.

Note: Low pressure gas engines are equipped with two carburetors and two regulators. The differential pressure between the two regulators must be within 1 inch of water. The optimum engine operation will occur when both the supply pressure for the regulator and the air/fuel differential pressure are close together.

9. Close the carburetor bypass valve (if equipped).

10. Allow the engine to reach full operating temperature. If necessary, adjust the carburetor bypass valve (if equipped). Obtain an idle rpm that is stable to a range of ± 2 rpm.

11. Increase the load while you monitor the exhaust oxygen and the electronic service tool "Detonation" screen. If three or more detonation bars appear on the electronic service tool "Detonation" screen, the exhaust oxygen level may be too low. Turn the load adjustment screw clockwise in order to obtain the exhaust oxygen level that is given in the Engine Performance, LEBQ6169. If the detonation is still present, temporarily retard the ignition timing with the electronic service tool.

Note: Detonation may cause severe engine damage. Make all adjustments slowly and pay close attention to the level of the exhaust oxygen to and the electronic service tool "Detonation" screen.

12. Continue to increase the load until the desired load is reached. Do not exceed the maximum load that was determined in the ""Required Information" ". If the engine does not reach the desired load and the throttle is wide open, either the gas supply or the air supply is insufficient.



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If the exhaust oxygen level is high in comparison to the data in the Engine Performance Manual, the engine needs more gas. Turn the load adjustment screw counterclockwise in order to increase the gas supply. If the exhaust oxygen level remains high, increase the differential pressure setting of the gas pressure regulator. If the exhaust oxygen level is low, the engine needs more air. Turn the adjustment screw for the wastegate clockwise in order to increase the turbocharger boost pressure.

13. While the engine is at the desired load, adjust the load adjustment screw in order to obtain the exhaust oxygen level that is given in the Engine Performance, LEBQ6169 at 100 percent load. If the engine is equipped with an air/fuel ratio control, adjust the load adjustment screw so that the fuel metering valve is 80 percent open.

14. For industrial engines, turnsetscrew (8) for the wastegate in order to obtain a throttle angle of 55 degrees to 60 degrees at full load. For generator set engines, turn the setscrew for the wastegate in order to obtain a throttle angle between 60 degrees and 65 degrees at full load. It may be necessary to readjust the following components several times in order to obtain the correct throttle angle at full load and the correct exhaust oxygen level: the load adjustment screw, the differential pressure and the wastegate. When the adjustment is complete, tighten nut (7) and install plug (6) .

Note: The throttle angle is measured with the scribed line that is on the throttle plate shaft. An open throttle corresponds to a 90 degree angle and the reference line that points straight up.

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Illustration 9 g00570073Wastegate

(6) Plug

(7) Nut

(8) Setscrew



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15. If the idle rpm is unstable or if the engine is difficult to start, adjust the carburetor bypass valve (if equipped). If the problem in the Impco carburetor is not resolved, you may add 7E-1569 Washers in order to lean the air/fuel ratio during the start and the idle. This addition will have little effect under load.

16. Operate the engine throughout the expected load range. Verify that the engine rpm is stable, and verify that the throttle angle at full load and the exhaust oxygen level are correct. Verify that the pressure in the gas supply line for low pressure systems is within 1.7 kPa (0.25 psi) at the no-load speed and at the full load speed. Verify that the pressure in the gas supply line for high pressure systems is within 6.9 kPa (1 psi) at the no-load speed and at full load speed. If the pressure in the gas supply line is within acceptable limits, the governor settings may need to be adjusted. Refer to the service literature for your governor.

17. Check the final adjustments to the engine in order to ensure compliance with the emissions requirement. Use a NOx meter or a CO meter, or use both of these meters together in order to perform this check.

Air/Fuel Ratio Control for a High Pressure Carburetor (Single Engine)

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(1) Actuator closed position



1. Turn on battery power to the engine.

2. Refer to Troubleshooting, SENR6413 for programming instructions for the Air/Fuel Ratio Control.

Note: All the parameters that are outlined in this section must be entered in order for the control to be programmed. If the value that is shown is the value which is desired, then change the setting. After you change the setting, then change the setting back to the original number. If the change is not made, you will receive the diagnostic code 591-12, "Engine Control Module Memory Failure" or "Module Not Programmed".

3. Calibrate the oxygen sensor. Refer to Troubleshooting, SENR6413.

4. If you are you are using DDT, go to Step 5 through Step 9. If you are you are using Cat ET, go to Step 10 through Step 13.

5. Press the "SELECT MODE" key on the DDT.

6. Press the "6" key on the DDT.


8. Press the "ENTER" key on the DDT.

9. Select "DISABLED" by pressing the "ALT1" key on the DDT. The A/F Ratio Control will now be disabled.

Note: Make sure that the A/F Ratio Control Actuator is showing 100 percent open when the control is disabled. Otherwise wait until initial start-up and set the Desired Full Load O2 (screen 30 on the DDT) to 1.0 percent. Then disable the control when it shows 100 percent open. The goal is to have the A/F Ratio Control valve completely open so that fuel flow is not resricted while you set up the engine.

10. Enter the "CONFIGURATION" screen in Cat ET.

11. Select the "FUEL RATIO" parameter.

12. Select the "CHANGE" button.

13. Select the "DISABLE" button.

(2) Actuator open position

(3) Valve closed position

(4) Valve open position

Hot engine components can cause injury from burns. Before performing maintenance on the engine, allow the engine and the components to cool.



14. Start the engine.

15. Increase from low idle to high idle.

16. Calibrate the timing. Refer to Troubleshooting, SENR6413.

17. Set the pressure differential for the gas pressure regulator. Refer to Systems Operation, Testing and Adjusting, SENR6412.

Note: Use this Special Instruction in order to set up all engine parameters. In addition to this Special Instruction, refer to Troubleshooting, SENR6413 and Specifications, SENR6417.

18. Slowly increase to 100 percent load. Set the carburetor and the wastegate. Refer to ""Adjustment Procedure for the High Pressure Carburetor and the Low Pressure Carburetor" ".

19. Use an emission analyzer tool to verify that the NOx emissions are set to the desired value at 100 percent load. Adjust the carburetor and the wastegate accordingly.

20. Verify that the reading for the oxygen sensor is displayed on the electronic service tool. The status screen will be displaying a value for the oxygen sensor that is within 1 percent of the measured value from the emission analyzer tool. If the value is not correct, then troubleshoot your oxygen sensor and your emission analyzer tool in order to determine the problem.

21. Ensure that the following readings are within one percent of each other.

"ACT OXYGEN"

"OXYGEN SENSOR"

22. Adjust the "Desired Full Load Oxygen" until the "ACT" O2 values are the same (0.4 percent of O2 from each other).

Note: The engine operation will not change. All of the settings as well as, speed, load, O2 percent, and the sound of the engine should remain the same. If any of the settings change, then troubleshoot the problem. By setting the "ACT/DES" O2 within 0.4 percent of each other, this will cause the control to make very minor adjustments once the control is turned on. If the settings are outside the 0.4 percent range and the control is enabled, the potential exists for the control to lean out or richen up the engine too quickly. This process may cause instability.

23. Turn the load adjustment screw for the carburetor counterclockwise until the air/fuel ratio control actuator shows between 60 percent and 80 percent open.

Note: If you have a low pressure air/fuel ratio control system, you will need to adjust the load adjustment screw for the carburetor on both carburetors by the same amount.

Air/Fuel Ratio Control for the Low Pressure Carburetor (Tandem Engine)

Note: Two electronic service tools are required for this setup procedure. You will also need two multimeters. One multimeter is needed for each signal from the governor actuators.

Using the DDT to Disable air/fuel ratio control



1. Start the tandem genset.




5. Select "DISABLED" by pressing the "ALT1" key on the DDT. Both controls are now 100 percent open.

Using Cat ET to disable air/fuel ratio control





5. Select the "DISABLE" button.

1. Ensure that both engines are firing by taking exhaust port temperatures. Temperatures should be within 100 °C (212 °F) of each other.

2. Increase from low idle to high idle.

Note: If the speed stability is not correct, then you will need to set all of the engine fuel pressure regulators to the same setting. A tandem engine high pressure fuel system has two regulators. A low pressure fuel system has four regulators. Refer to Systems Operation, Testing and Adjusting, SENR6412 for information on adjustments for the fuel pressure regulator.

3. Check the speed stability and set the speed stability.

Note: Adjust the remote panel load balance control potentiometer on the slave ecm until both the COM 1 and COM 2 LED lights are on. In manual mode, the load balance control potentiometer offsets the governor output from the master ECM to the slave ECM. In the automatic mode, the load balance control potentiometer offsets the manifold pressure signal from the master ECM to the slave ECM.

4. Set the "Load Control Switch" on the slave remote panel to "MANUAL".

5. Increase load in 25 percent increments. Increase load to 25 percent. Increase up to 75 percent.

6. Decrease load in 25 percent increments. Return to original load setting.

7. Using the meter, take another reading of both of the signals for the governor actuators. Both engines must have the same meter reading. Adjust the governor linkage if the readings for the actuator and the readings for the throttle are not the same.

Note: Troubleshoot the engine if problems are encountered when adding more than a 50



percent load to the engine. Also, troubleshoot the fuel supply system if problems are encountered when adding more than 50 percent load to the engines.

8. Repeat steps 5 through 7 until the two current meter readings are identical throughout the load range.

Note: A load that remains below 75 percent load is not influenced by the wastegates.

9. Set the load to 100 percent.

10. Use an emissions analyzer and set the exhaust oxygen sensor at full load.

11. Set the load to 105 percent.

12. Adjust each engine's wastegate until the engines' throttles are wide open.

13. Set load back to 100 percent.

14. If necessary, reset the oxygen sensors to full load.

15. Change the "Load Control Switch" of the slave remote panel from "MANUAL" to "AUTO".

16. Verify that the engines have the same throttle angle. Also verify that the engines have the same intake manifold air pressure. Return to the "MANUAL" mode and troubleshoot the problem if the throttle angles are not the same. If the intake manifold pressures are not the same, then return to the "MANUAL" mode and troubleshoot the problem.

17. Adjust the "DES FULL LOAD" O2 value so that the "ACT/DES" O2 values are within 0.4 percent of O2 from each other. This must be done for both engines.

Using the DDT to enable air/fuel ratio control




4. Select "ENABLED" by pressing the "ALT1" key on the DDT.

Using Cat ET to enable air/fuel ratio control





5. Select the "ENABLE" button.

1. Adjust each carburetor. Make the same adjustments on both carburetors. Set the actuator for



the air/fuel ratio control to between 60 percent and 80 percent.

2. The air/fuel ratio controls and the engines are now setup for operation.

Starting the Engine

1. Perform a fluid level check of engine oil, and of the coolant.

Note: Jacket water coolant temperature needs to be above 70 °C (158 °F).

2. Check the Status Control Panel, the electronic service tool, and the switch gear for the generator for faults.

3. Open the manual fuel shutoff valve to the open position.

4. Turn the key switch for the generator to the ON position.

5. Turn the engine control switch to the IDLE position.

6. Turn the engine control switch from the OFF/RESET position to the AUTO position.

7. Turn the engine control switch from the AUTO position to the MANUAL position. Start the engine. If the engine fails to start, repeat the above step.

8. Turn the idle/rated switch from the IDLE position to the RATED position.

Engine exhaust contains products of combustion which may be harmful to your health. Always start and operate the engine in a well ventilated area and, if in an enclosed area, vent the exhaust to the outside.

NOTICEFor initial start-up of a new or rebuilt engine, and for start-up of an engine that has been serviced, make provision to shut the engine off should an overspeed occur. This may be accomplished by shutting off the fuel supply and/or the ignition to the engine.

Unburned gas in the air inlet and exhaust system may ignite when the engine is started. Personal injury and/or damage may result.

Before starting an engine that may contain unburned gas, purge the unburned gas from the air inlet and exhaust system. Refer to "Unburned Gas - Purge".



Note: If stability problems are encountered, then the fuel is probably too rich. Stability problems can also be encountered if the fuel is too lean. The rich fuel mixture can be reduced by closing the manual butterfly valve. If the engine slowly loses power, the fuel is too lean. Decrease the engine rpm until you obtain a 60 percent air/fuel ratio control position.

Procedure for Shutting Down the Engine 1. Take load off the engine.

2. Turn the idle/rated switch from the RATED position to the IDLE position.

3. Turn the engine control switch from the MANUAL position to the COOL DOWN/STOP position.

4. When the "Status Control Panel" initiates shutdown, close the manual fuel shutoff valve.

Adjustment Procedure for Carburetor and Zero Pressure Regulators Note: Gas can leak through the zero pressure regulator into the fuel system when the gas shutoff valve is open. Do not leave the shutoff valve for the gas in the open position for a longer time than the time necessary to make adjustments. Before you start the engine, purge the inlet system and the exhaust system by disabling the ignition system. Then crank the engine with the gas supply OFF for one crank cycle.

1. Ensure that the throttle linkage is adjusted correctly. Use the 1P-2385 Protractor to make this adjustment. Refer to the ""Carburetor Control Linkage (EG-3P Actuator)" " section for details.

2. Use the electronic service tool in order to program the ignition timing. Refer to ""Ignition Timing" " for details on determining the correct setting for the ignition timing. Program all other specified parameters. Refer to Troubleshooting, SENR6413.

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3. Loosen locknut (10) and turn load adjusting screw (9) clockwise to the OFF position.

4. Set the pressure from the gas supply line to the pressure regulator to 3 kPa (0.45 psi) to 7 kPa (1.05 psi).

Illustration 11 g00570173Carburetor

(9) Load adjusting screw

(10) Locknut

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5. Remove cover (12) and cap (15) from the pressure regulator.

6. Open the gas shutoff valve in order to supply gas to the pressure regulator.

7. If necessary, turn screw (14) the under cap counterclockwise in order to ensure that no gas

Illustration 12 g00529472Zero pressure regulator

(11) Valve

(12) Cover

(13) Seat

(14) Screw

(15) Cap



flows out of valve (11) .

8. Turn screw (14) clockwise in order to begin to lift valve (11) off valve seat (13). The flow of gas is now heard in regulator valve (11) .

9. De-energize the gas shutoff valve. Install cover (12) .

10. Turn load adjusting screw (9) four times in the counterclockwise direction. These turns open the fuel passage. Tighten locknut (10) .

11. Start the engine and verify that the supply pressure to the regulator is within 3 kPa (0.45 psi) to 7 kPa (1.05 psi) above zero. Continue to run the engine at low load in order to reach the normal operating temperature.

Note: Open the gas shutoff valve after you crank the engine for three to five seconds. This action will achieve the best performance at starting.

12. Adjust the exhaust oxygen level at low load and at high idle to three to five percent. Use load adjusting screw (9) for the regulator in order to make this adjustment.

13. Install cap (15) for the regulator.

14. Increase the load on the engine until you reach approximately 25 percent load. Adjust the load adjusting screw (9) in order to obtain an exhaust oxygen level of 6 percent.

Note: Detonation may cause severe engine damage. Make all adjustments slowly and pay close attention to the exhaust oxygen level and the electronic service tool "Detonation" screen.

15. Increase the load on the engine to approximately 50 percent of the load. Use load adjusting screw (9) to adjust the exhaust oxygen level. Adjust the exhaust oxygen level to the 50 percent rating that is given in the Engine Performance, LEBQ6169.

16. Increase the load to the desired load while you monitor the exhaust oxygen level and the electronic service tool "Detonation" screen. If three or more detonation bars appear on the screen, check the exhaust oxygen level. Slowly turn load adjusting screw (9) in order to obtain the exhaust oxygen level at the 100 percent load that is given in the Engine Performance, LEBQ6169. If the detonation is still present, temporarily retard the ignition timing with the electronic service tool.

For high altitude applications, it may be necessary to adjust the wastegate in order to reach the desired load.

17. While the engine is at full load, adjust load adjusting screw (9) in order to obtain the desired NOx level.

18. Operate the engine at low load and at high idle rpm. If necessary, readjust the adjusting screw (14) for the regulator in order to obtain a three to five percent exhaust oxygen level.

19. Operate the engine at full load and readjust the NOx level, if necessary.

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20. Turn setscrew (18) for the wastegate in order to obtain an 80 percent open throttle at full load. If necessary, readjust the main adjustment screw and the wastegate several times in order to obtain the correct throttle angle at full load and the correct NOx level.

21. Stop the engine and start the engine several times. If the engine is difficult to start, repeat this procedure starting with Step 7.

22. Operate the engine throughout the expected load range. Verify that the engine rpm is stable. Verify that the throttle angle at full load and the NOx level are correct. If the engine rpm is unstable, readjust the settings of the governor, if necessary.

Cooling System

Jacket Water Heater

Reduced life and failure of jacket water heaters can normally be traced to incorrect installation or to incorrect electrical hookups. The following conditions are the major problem areas.

Hose Installation

The installation or routing of hoses is most often the cause of jacket water heater problems. The hose routing can be incorrect due to original installation, movement of hoses during repair, or rerouting of hoses around other equipment. Illustrations 14 and 15 show examples of hose routing.

Illustration 13 g00570287Wastegate

(16) Plug

(17) Nut

(18) Setscrew



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The hoses for the jacket water heater must slant upward from the heater connection to the engine connection. This is especially important on the heater outlet hose. Any loop or high point in the water outlet hose can result in a steam pocket that will stop all coolant circulation.

Failure of the Thermostat

Poor coolant circulation, incorrect voltage, and poor electrical connections are all potential problem areas that can shorten thermostat life. Poor coolant circulation can be caused by incorrect hose installation or a restriction in one of the hoses. Poor coolant circulation will cause the thermostat to cycle rapidly. The life of the thermostat will be reduced if the thermostat cycles two or more times in 15 minutes.

A voltage of more than 20 percent above the rated voltage will shorten the service life of the thermostat and of the heater element. Make sure that 120 volt jacket water heaters are connected to a 120 volt source and that 240 volt jacket water heaters are connected to a 240 volt source.

Poor electrical connections can cause the thermostat to overheat. Poor electrical connections can cause the thermostat to fail. This is more likely to occur with a 120 volt jacket water heater. Use number ten wire and 2L-8066 Terminals to install a 120 volt jacket water heater. Caterpillar recommends that all connections be soldered.

Heater Element Failure

Short service life of heater elements is normally due to excessive voltage or to a lack of coolant




around the element. The 240 volt elements have a resistance of approximately 19.2 ohms. The 120 volt elements have a resistance of approximately 4.8 ohms. Connecting a jacket water heater to a voltage supply that is 20 percent or more above the rated voltage will shorten the life of the heater elements and of the thermostats.

Note: Make sure that the jacket water heaters are filled with coolant before the heaters are connected.

Insufficient Heating

The most common cause of insufficient heating of the engine block is due to incorrect hose installation. This condition is described in the section ""Hose Installation" ". Rapid cycling of the thermostat would indicate incorrect hose installation.

Low supply voltage will reduce heating. If the voltage is 20 percent below the rated level, the power (wattage) is 36 percent below the rated wattage. Small reductions in voltage due to long undersized wire have a significant effect on heater wattage.

In some cases, coolant will circulate between the jacket water heater and the engine, but only one area of the engine is warmed. If this occurs the inlet and outlet lines for the jacket water heater must be routed to other points on the engine. Make sure that the heated coolant from the jacket water heater does not enter the engine too close to the engine thermostats. If the heated coolant enters the engine too close to the engine thermostats, the engine thermostats will open. This will allow circulation through the radiator.

Unburned Gas − Purge The following events cause unburned gas to remain in the air inlet and in the exhaust manifold:

Emergency stop

Engine overspeed

Unsuccessful successive attempts to start the engine

Unburned gas may remain in the air inlet and exhaust system after several unsuccessful attempts to start the engine. The unburned gas may increase to a concentration that may ignite during a successive attempt to start the engine.

Perform the following procedure in order to purge the unburned gas:

1. Turn the manual gas shutoff valve to the CLOSED position.

2. Disable the ignition by disconnecting one of the wires that is labelled "M200" from the emergency stop button.

3. Turn the engine control switch to the START position. Crank the engine for one full crank cycle in order to purge the unburned gas.

4. Enable the ignition by connecting the wire that was disconnected in Step 2.

5. Turn the manual gas shutoff valve to the OPEN position.



6. Continue with your previous procedure.

Gas Engine Troubleshooting Data Sheet Complete this sheet before you call the Caterpillar Dealer Solution Network.

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Illustration 16 g

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