C7.1 Industrial Engine and Generator Set Caterpillar

Note: If the fault is intermittent and the fault cannot be duplicated, refer to Troubleshooting, "Power Is Intermittently Low or Power Cutout Is Intermittent".

Note: If the fault only occurs under certain conditions, test the engine under those conditions. Examples of certain conditions are high rpm, full load, and engine operating temperature. Troubleshooting the symptoms under other conditions can give misleading results.

Probable Causes

• Diagnostic codes

• Throttle position sensor

• Air intake and exhaust system

• Fuel supply

• Fuel injection pump

• Low compression (cylinder pressure)

• Electronic unit injectors

• Individual malfunctioning cylinder

Recommended Actions

Diagnostic Codes

Use one of the following methods to check for active diagnostic codes:

• The electronic service tool

• The display on the control panel

• Flash Codes

Electronic Service Tool

1. Connect the electronic service tool to the diagnostic connector.

2. Check for active diagnostic codes on the electronic service tool.

3. Investigate any active codes before continuing with this procedure. Refer to Troubleshooting, "Troubleshooting with a Diagnostic Code".

Display on the Control Panel

Note: The following procedure is only applicable if the application is equipped with a display on the control panel.

1. Check the display on the control panel for active diagnostic codes.

2. Troubleshoot any active codes before continuing with this procedure. Refer to Troubleshooting, "Troubleshooting with a Diagnostic Code".

Flash Codes

Note: The following procedure is only applicable if the machine is equipped with the appropriate warning lamps.

1. Check the warning lamps on the control panel for flash codes. Flash codes are explained in Troubleshooting, "Flash Codes".

2. If any flash codes are displayed, troubleshoot the codes before continuing with this procedure. Refer to Troubleshooting, "Troubleshooting with a Diagnostic Code".

Throttle Position Sensor

1. Use the electronic service tool and observe the signal for the throttle position sensor. Make sure that the throttle reaches the 100% raw position and the calibrated position.

2. If the signal is erratic, refer to Troubleshooting, "Analog Throttle Position Sensor Circuit - Test" or Troubleshooting, "Digital Throttle Position Sensor Circuit - Test".

3. If the engine has a throttle switch, refer to Troubleshooting, "Throttle Switch Circuit - Test".

4. If the repairs do not eliminate the fault, proceed to "Air Intake and Exhaust System".

Air Intake and Exhaust System

1. Check the air filter restriction indicator, if equipped.

2. Ensure that the air filter is clean and serviceable.

3. Check the air intake and exhaust systems for the following defects:

   • Blockages

   • Restrictions

   • Damage to lines or hoses

4. If the repairs do not eliminate the fault, proceed to "Fuel Supply".

Fuel Supply

1. Visually check the fuel tank for fuel. The fuel gauge may be faulty.

2. Ensure that the fuel supply valve (if equipped) is in the full OPEN position.

3. If the temperature is below 0 °C (32 °F), check for solidified fuel (wax).

4. Check the primary filter/water separator for water in the fuel.

5. Check for fuel supply lines that are restricted.

6. Check that the low-pressure fuel lines are tight and secured properly.

7. Replace the in-line fuel strainer that is installed upstream of the Electric Fuel Lift Pump (EFLP).

8. Check that the EFLP is operating. If the EFLP is suspect, refer to Troubleshooting, "Fuel Pump Relay Circuit - Test".

9. Check the fuel filters.

10. Check the diesel fuel for contamination. Refer to Systems Operation, Testing, and Adjusting, "Fuel Quality - Test".

11. Check for air in the fuel system. Refer to Systems Operation, Testing, and Adjusting, "Air in Fuel - Test".

12. Ensure that the fuel system has been primed. Refer to Systems Operation, Testing, and Adjusting, "Fuel System - Prime".

13. If the fault is not eliminated, perform the following procedure:

    Note: Before performing the following fuel system tests, the engine must be run for a minimum of 30 minutes.

    Note: When performing the following fuel system tests, the Electric Fuel Lift Pump (EFLP) will only operate for 2 minutes unless the engine is running. If necessary, cycle the keyswitch in order to reactivate the pump.

Illustration 1	g02873776
(1) Return line pressure relief valve (2) Secondary fuel filter base (3) Transfer pump inlet regulator (TPIR) (4) Transfer pump inlet regulator return port

Transfer Pump Inlet Regulator (TPIR) Flow Test

Refer to Illustration 1.

Perform the following procedure:

1. Make sure the keyswitch is in the OFF position.

2. Disconnect the TPIR return line from the drain port on the TPIR. Install a suitable blanking cap on the open port in the TPIR return line

3. Connect a temporary drain line to the drain port on the TPIR.

4. Place the end of the temporary drain line into a suitable calibrated container.

5. With the keyswitch in the ON position but the engine not running, use a suitable multimeter to measure the input voltage to the EFLP. Record the reading.

6. With the keyswitch in the ON position but the engine not running, measure the fuel flow from the temporary drain line. For a 12 VDC system, refer to Illustration 2 for the minimum acceptable flow rate. For a 24 VDC system, refer to Illustration 3 for the minimum acceptable flow rate.
   Show/hide table

   Illustration 2	g02355128
   Minimum TPIR flow rate for a 12 VDC system

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   Illustration 3	g02355130
   Minimum TPIR flow rate for a 24 VDC system

7. Remove the temporary drain line from the drain port on the TPIR. Connect the TPIR return line to the TPIR.

8. If the fuel flow in Step 6 is greater than the minimum limit, proceed to "Fuel Injection Pump".

9. If the fuel flow in Step 6 is below the minimum limit, proceed to "Return Line Pressure Relief Valve Test".

10. If there is no fuel flow in Step 6, proceed to "Transfer Pump Inlet Regulator (TPIR) Return Test".

Transfer Pump Inlet Regulator (TPIR) Return Test

In order to check the return flow from the TPIR, perform the following procedure:

1. Make sure that the TPIR return line is not blocked or kinked.

2. If the TPIR return line is clear, confirm that the Electric Fuel Lift Pump (EFLP) is operating. Make sure that fuel lines between the EFLP and the TPIR are not blocked or kinked.

3. If the fuel lines to the TPIR are clear and the EFLP is operating, replace the TPIR.

4. If the fault is still present, proceed to "Fuel Injection Pump".

Return Line Pressure Relief Valve Test

In order to check the return line pressure relief valve in the secondary fuel filter base, perform the following procedure:

1. Make sure the keyswitch is in the OFF position.

2. Disconnect the return line banjo connection on the top of the secondary fuel filter.

3. Use a suitable blank to plug the return line.

4. Install a suitable drain line to the return line point on the top of the secondary fuel filter.

5. Place the open end of the drain line in a suitable calibrated container.

6. With the keyswitch in the ON position, measure the flow from the drain line.

7. If the flow from the drain line is less than 0.4 L (24.4 cubic inch) per minute, proceed to "EFLP Flow Test at the Primary Fuel Filter Inlet".

8. If the flow from the drain line is more than 0.4 L (24.4 cubic inch) per minute, replace the secondary fuel filter head. Refer to Disassembly and Assembly, "Fuel Filter Base - Remove and Install".

EFLP Flow Test at the Primary Fuel Filter Inlet

In order to check the fuel flow from the EFLP at the primary fuel filter inlet, perform the following procedure:

1. Make sure the keyswitch is in the OFF position.

2. Disconnect the fuel inlet connection from the primary fuel filter head.

3. Install a suitable blank on the fuel inlet port on the primary fuel filter head.

4. Place the open end of the fuel inlet line in a suitable calibrated container.

5. With the keyswitch in the ON position, measure the input voltage at the EFLP. Record the result.

6. With the keyswitch in the ON position, measure the flow from the fuel inlet line. Record the result.

7. Check the recorded voltage and fuel flow on the graph in Illustration 4
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   Illustration 4	g02527498
   Minimum EFLP flow rate for a 12 VDC system

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   Illustration 5	g02527518
   Minimum EFLP flow rate for a 24 VDC system

8. If the fuel flow is below the minimum value for the recorded voltage, replace the EFLP. Refer to Disassembly and Assembly, "Fuel Priming Pump - Remove and Install ".

9. If the fuel flow is above the minimum value for the recorded voltage, proceed to "Check the Return Fuel Lines".

Check the Return Fuel Lines

1. Make sure that the TPIR return line is not blocked or kinked.

2. Make sure that fuel lines between the EFLP and the TPIR are not blocked or kinked.

3. If the fuel lines to the TPIR are clear and the EFLP is operating, replace the TPIR.

4. If the fault is still present, proceed to "Fuel Injection Pump".

Fuel Injection Pump

Note: The fuel injection pump that is installed by the factory is a nonserviceable item. If any fault occurs within the fuel injection pump, the fuel injection pump must be replaced.

1. Use the electronic service tool to select the correct screen in order to display any diagnostic trouble codes that relate to the fuel injection pump. Refer to Troubleshooting, "Troubleshooting with a Diagnostic Code".

2. If the fault is not eliminated, refer to "Low Compression (Cylinder Pressure)".

Low Compression (Cylinder Pressure)

1. Perform a compression test. Refer to Systems Operation, Testing, and Adjusting, "Compression - Test ".

2. If low compression is noted on any cylinders, investigate the cause and rectify the cause.

   Possible causes of low compression are shown in the following list:

   • Loose glow plugs

   • Faulty piston

   • Faulty piston rings

   • Worn cylinder bores

   • Worn valves

   • Faulty cylinder head gasket

   • Damaged cylinder head

3. Perform all necessary repairs.

4. Ensure that the repairs have eliminated the faults.

5. If the repair does not eliminate the fault, refer to "Electronic Unit Injectors".

Electronic Unit Injectors

1. Use the electronic service tool to perform the automatic "Cylinder Cut Out Test". If the compression test that was performed in "Low Compression (Cylinder Pressure)" was satisfactory, the "Cylinder Cut Out Test" will identify any faulty injectors.

2. Remove any faulty electronic unit injectors. Refer to Disassembly and Assembly, "Electronic Unit Injector - Remove".

3. Install a new electronic unit injector. Refer to Disassembly and Assembly, "Electronic Unit Injector - Install".

4. Repeat the test in 1. If the fault is still apparent, remove the replacement electronic unit injector and install the original electronic unit injector. Refer to Disassembly and Assembly, "Electronic Unit Injector - Remove" and Disassembly and Assembly, "Electronic Unit Injector - Install".

5. If all injectors have been checked and no faults are detected, proceed to "Individual Malfunctioning Cylinders".

Individual Malfunctioning Cylinders

1. With the engine speed at a fast idle, use the electronic service tool to perform the manual "Cylinder Cut Out Test". As each cylinder is cut out, listen for a change in the sound from the engine. When a cylinder is cut out, there should be a noticeable change in the sound of the engine. If a change in the sound of the engine is not noted, the isolated cylinder is not operating under normal conditions. If a change in the sound of the engine is less noticeable, the cylinder may be operating below normal performance. Investigate the cause of the fault on any cylinder that is not operating. Investigate the cause of the fault on any cylinder that is operating below normal performance.

2. If the fault is not eliminated, contact the technical communicator at a Cat dealer.