C7 and C9 On-Highway Engines Caterpillar

Fuel System Pressure - Test

Usage:

C7 C7S

System Operation Description:

The fuel system provides the engine and the Aftertreatment Regeneration Device (ARD) with pressurized fuel. This procedure verifies that the fuel system is working correctly. This procedure also troubleshoots the following diagnostic trouble codes:

157-17 Engine Injector Metering Rail 1 Pressure : Low - Least Severe (1)
1239-0 Engine Fuel Leakage : High - Most Severe (3)

The fuel system has a low-pressure side and a high-pressure side. Refer to Illustration 1.

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Illustration 1	g02057673
Fuel system schematic (1) Cylinder head (2) 550 kPa (80 psi) regulator (3) Fuel rail pressure sensor (4) Lines between the rail and the cylinder head (5) Rail (6) Pressure relief valve (7) 600 kPa (86 psi) regulator for the high-pressure fuel pump (8) High-pressure fuel pump (9) Fuel transfer pump (10) Fluid sampling valve (11) Secondary fuel filter (12) Backflow check valve (13) Optional hand priming pump (14) Fuel filter base (15) Forward fuel manifold (16) 1250 kPa (180 psi) pressure regulator (17) 500 kPa (72 psi) pressure regulator (18A) Fuel enable valve in the de-energized position (18B) Fuel enable valve in the energized position (19) Main fuel control solenoid (20) Pilot fuel control solenoid (21) Rear fuel manifold (22) Pilot fuel pressure sensor (23) Main fuel pressure sensor (24) Primary fuel filter (25) Fuel tank

Low Pressure Fuel System - The low-pressure fuel system provides a fuel pressure of approximately 480 kPa (70 psi) to high-pressure fuel pump (8) . The low-pressure fuel system provides a fuel pressure of approximately 1700 kPa (250 psi) at solenoids (19) and (20) for the ARD when the ARD is on.

High Pressure Fuel System - The high-pressure fuel system provides fuel at high pressure for the injectors. The pressure depends on the engine operating conditions. The actual fuel pressure can be viewed on the Caterpillar Electronic Technician (ET).

The vehicle fuel tank (25) provides fuel for cylinder head (1) and for the ARD. Primary fuel filter (24) is a 10 micron filter. All of the fuel for the cylinder head and for the ARD passes through the primary fuel filter. Fuel transfer pump (9) pressurizes the fuel.

Fuel Enable Valve (18)

This valve is controlled by the Engine Control Module (ECM). The valve has two positions. The following paragraphs describe each position.

De-Energized Position (18A) - 1250 kPa (180 psi) regulator (16) is bypassed by a passage in the valve. Fuel cannot flow to solenoids (19) and (20) . Regulator (17) establishes the fuel pressure at the inlet of fuel filter base (14) at approximately 500 kPa (72 psi).

Energized Position (18B) - The 1250 kPa (180 psi) regulator (16) is now part of the system. The fuel transfer pump develops a fuel pressure of approximately 1700 kPa (250 psi). This pressure is regulated by 1250 kPa (180 psi) regulator 16 kPa and 500 kPa (72 psi) regulator (17) . Fuel at this pressure is routed to solenoids (19) and (20) through a passage in valve (18) . Fuel at approximately 500 kPa (72 psi) continues to be supplied to the inlet of the fuel filter base.

Optional hand priming pump (13) provides a means for removing air from the system. Backflow check valve (12) prevents fuel from draining from the high-pressure fuel pump when the engine is not running. Secondary fuel filter (11) is a 2 micron filter. All of the fuel for the cylinder head passes through the secondary fuel filter. Fluid sampling valve (10) provides a port for taking fuel samples and for measuring fuel pressure.

High-pressure fuel pump (8) creates high fuel pressure for the engine. Regulator (7) establishes an internal operating pressure of 600 kPa (86 psi) for the high-pressure fuel pump. Excess fuel flows through regulator (7) to the vehicle fuel tank.

Fuel rail pressure sensor (3) sends a signal to the ECM. The signal indicates the fuel pressure inside rail (5) . Pressure relief valve (6) relieves excess pressure in the rail, if necessary. Regulator (2) establishes a fuel pressure of approximately 550 kPa (80 psi) inside the cylinder head. The fuel injectors require this return pressure in order to operate correctly.

Component Identification

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Illustration 2	g03780031
Left side of the engine Regulator (7) is behind pump (8) . (1) Cylinder head (2) 550 kPa (80 psi) regulator (3) Fuel rail pressure sensor (4) Lines between the rail and the cylinder head (5) Rail (6) Pressure relief valve (8) High-pressure fuel pump (9) Fuel transfer pump (10) Fluid sampling valve (11) Secondary fuel filter (12) Backflow check valve (13) Optional hand priming pump (14) Fuel filter base (15) Forward fuel manifold (16) 1250 kPa (180 psi) pressure regulator (17) 500 kPa (72 psi) pressure regulator (18) Fuel enable valve (19) Main fuel control solenoid (20) Pilot fuel control solenoid (21) Rear fuel manifold (22) Pilot fuel pressure sensor (23) Main fuel pressure sensor

Lines and Ports

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Illustration 3	g01444224
Configuration for C7 engines and C9 engines that are not installed in recreational vehicles (26) Line from the outlet of the fuel filter base to the inlet of the high-pressure fuel pump (27) Inlet to the high-pressure fuel pump (28) Line from the outlet of the high-pressure fuel pump to the rail (29) Port for pressurized oil for the high-pressure fuel pump (30) Line from the forward manifold to the inlet of the fuel transfer pump (31) This support provides a passage for return fuel from regulator (7) to vehicle fuel tank. (32) Line for return fuel from regulator (7) to the vehicle fuel tank (33) Line for return fuel from the cylinder head (34) Line for return fuel from the rail (35) Port for purge air to the ARD (36) Ports for return fuel to the vehicle fuel tank (37) Line from the forward fuel manifold to the inlet of the fuel filter base (38) Fuel line from the primary fuel filter (39) Line from the outlet of the fuel transfer pump to the forward fuel manifold (40) Line for main fuel to the rear fuel manifold (41) Line for pilot fuel to the rear fuel manifold

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Illustration 4	g01444231
Configuration for C9 engines that are installed in recreational vehicles (27) Inlet to the high-pressure fuel pump (28) Line from the outlet of the high-pressure fuel pump to the rail (29) Port for pressurized oil for the high-pressure fuel pump (30) Line from the forward manifold to the inlet of the fuel transfer pump (32) Line for return fuel from regulator (7) to the vehicle fuel tank (33) Line for return fuel from the cylinder head (34) Line for return fuel from the rail (35) Port for purge air to the ARD (36) Ports for return fuel to the vehicle fuel tank (37) Line from the forward fuel manifold to the inlet of the fuel filter base (39) Line from the outlet of the fuel transfer pump to the forward fuel manifold (40) Line for main fuel to the rear fuel manifold (41) Line for pilot fuel to the rear fuel manifold (42) Line for fuel from the fuel transfer pump via the rear fuel manifold (43) Port for fuel from the primary fuel filter

Diagnostic Tests

The Caterpillar Electronic Technician (ET) has four diagnostic tests for the fuel system:

"Fuel System Functional Test" - This test can only be performed when the engine is running. This test runs for a maximum of 35 seconds. This test checks several items. First, the test determines if the mechanical timing of the high-pressure fuel pump is incorrect. Then, the test determines if either side of the high-pressure fuel pump is not working correctly. Finally, the test checks for leaks in the high-pressure fuel system. The checks for leaks are performed at two different rail pressures.

Fuel System Verification Test - This test evaluates the health of each injector. The test determines if an injector needs to be replaced. When the test is performed, Cat ET indicates the status of each injector as "Success" or "Failed". Perform this test immediately after an injector has been replaced. Also, perform this test if a –2 code is active or a –7 code is active.

"Injector Fuel Delivery Test" - This test runs for a maximum of 9 minutes. This test helps determine if an injector is causing an engine performance problem. The ability of each injector to deliver a certain amount of fuel is tested. This test helps identify problems with injectors at higher rail pressures. Each injector is tested at various rail pressures.

"Cylinder Cutout Test" - This test runs for a maximum of 8 minutes. This test helps determine if an injector is causing an engine performance problem. The ability of each injector to deliver a certain amount of fuel is tested. This test helps identify problems with injectors at lower rail pressures. Each injector is tested at various rail pressures.

Test Step 1. Inspect the High Pressure Fuel Pump

If you are troubleshooting one of the following performance complaints, perform this troubleshooting procedure only after you have checked all other possible causes of the complaint.

"Acceleration is Poor or Throttle Response is Poor"
"Engine Misfires, Runs Rough or Is Unstable"
"Engine Shutdown Is Intermittent"
"Engine Top Speed Is Not Obtained"
"Vehicle Top Speed is Not Obtained"

If the engine is running, stop the engine.

Inspect the exterior of the high-pressure fuel pump. Look for evidence of fuel leaks.

Disconnect each harness connector from the pump. Look for fuel on the connectors.

Expected Result:

The pump has no external fuel leaks. Both connectors are free of fuel.

Results:

The pump has no external fuel leaks. Both connectors are free of fuel. - Proceed to Test Step 2.
A connector is contaminated with fuel. -
Repair: Fuel can cause the connector seal to expand. Try to plug the connector into the pump. Do not force the connector into the pump. Replace the connector seal if the connector does not plug into the pump with reasonable effort. The part number for the connector seal is 264-7029 Connector Seal . Also, replace the high-pressure fuel pump. Continue with this troubleshooting procedure after the pump and the connector seal have been replaced.
Proceed to Test Step 2.
The high-pressure fuel pump has an external fuel leak. -
Repair: Replace the high-pressure fuel pump. Be sure that the pump timing is correct. Crank the engine after the pump is installed.
Proceed to Test Step 2.

Test Step 2. Check Prior Maintenance, If Necessary

If the engine does not start and maintenance was performed on the fuel system, check the work that was performed on the fuel system. Look for these conditions:

Electrical connectors not connected.
Fuel lines not connected.
The high-pressure fuel pump is not correctly timed.

Expected Result:

Prior maintenance on the fuel system was performed correctly.

Results:

Prior maintenance on the fuel system was performed correctly. - Proceed to Test Step 3.
Prior maintenance was not performed correctly. -
Repair: Correct the problem.
Proceed to Test Step 3 when the problem is corrected.

Test Step 3. Replace the Fuel Filters

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Fuel leaked or spilled onto hot surfaces or electrical components can cause a fire. To help prevent possible injury, turn the start switch off when changing fuel filters or water separator elements. Clean up fuel spills immediately.

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NOTICE

Use a suitable container to catch any fuel that might spill. Clean up any spilled fuel immediately.

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NOTICE

Do not allow dirt to enter the fuel system. Thoroughly clean the area around a fuel system component that will be disconnected. Fit a suitable cover over disconnected fuel system component.

Replace the primary fuel filter and the secondary fuel filter.

Expected Result:

The fuel system has new fuel filters.

Results:

The fuel system has new fuel filters. - Try to start the engine. If the engine starts and you were troubleshooting a "engine does not start" complaint, the new fuel filters solved the problem. Otherwise, proceed to Test Step 4.

Test Step 4. Connect Tooling to the Fuel System

Note: Use pressure gauges that can indicate at least 2050 kPa (300 psi).

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Illustration 5	g01387516
Typical configuration (10) Fluid sampling valve

Note: Ensure that fluid sampling valve (10) is clean before you connect a pressure gauge to the valve.

Connect a pressure gauge to fluid sampling valve (10) .

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Illustration 6	g01444264
Location for connecting the tooling (39) Line from the outlet of the fuel transfer pump to the forward fuel manifold

Remove line (39) . Use flexible fuel lines and a tee fitting in order to connect the following tooling between the outlet of the fuel transfer pump and the forward fuel manifold:
- Pressure gauge
- 2P-8278 Tube As (SIGHT GAUGE) or equivalent
This configuration provides a pressure indication for the fuel that is flowing from the fuel transfer pump. This configuration also provides an indication of air in the system.

Expected Result:

The tooling is installed.

Results:

Continue to the next test step.

Test Step 5. Use the Hand Priming Pump, If Equipped

If the engine is not equipped with a hand priming pump, continue to the next test step.

If the engine is equipped with a hand priming pump, use the following procedure in order to prime the fuel system:

Check that the hand priming pump (13) is in the "ON" position. Operate the hand priming pump until a strong pressure is felt. This action may require considerable strokes. Lock the hand priming pump.

Expected Result:

The fuel system is primed.

Results:

Continue to the next test step.

Test Step 6. Check for Fuel Leaks

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Do not check for fuel leaks with your hands. Very small leaks can result in a high velocity fuel stream that will be invisible close to the leak. This fuel can penetrate the skin and cause personal injury. Use cardboard or paper to check for fuel leaks.

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NOTICE

Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again.

Crank the engine. The engine may start. If the engine does not start, check for leaks in the fuel system while the engine is cranking. If the engine starts, check for leaks after the engine starts.

Expected Result:

There are no external leaks in the fuel system.

Results:

There are no external leaks in the fuel system. - Proceed to the next test step.
The fuel system has an external leak. -
Repair: Fix the leak. Replace parts, if necessary.
Proceed to the next test step after all leaks have been repaired.

Test Step 7. Check the Condition of the Fuel System

Review this test step before you perform this test step.

If the engine starts or the engine is running, observe the pressure gauges and the sight gauge.

If the engine does not start, observe the pressure gauges and the sight gauge while the engine is cranking. Do not crank the engine for more than 30 seconds.

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Illustration 7	g01391837
Typical sight gauge

Determine the row in Table 1 that applies to the conditions.

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Table 1
Conditions for the Fuel System
Conditions			Procedure
The engine does not start.	The air flow in the sight gauge is not acceptable.		Perform Procedure "A".
	The air flow in the sight gauge is acceptable.	The pressure at the outlet of the fuel transfer pump is less than 50 kPa (7 psi). The pressure at the fluid sampling valve is less than 50 kPa (7 psi).	Perform Procedure "B".
		The pressure at the outlet of the fuel transfer pump is at least 50 kPa (7 psi). The pressure at the fluid sampling valve is less than 50 kPa (7 psi).	Perform Procedure "D".
		The pressure at the outlet of the fuel transfer pump is at least 50 kPa (7 psi). The pressure at the fluid sampling valve is at least 50 kPa (7 psi).	Perform Procedure "F".


The engine starts.	The air flow in the sight gauge is not acceptable.		Perform Procedure "A".
	The air flow in the sight gauge is acceptable.	The pressure at the outlet of the fuel transfer pump is less than 350 kPa (50 psi). The pressure at the fluid sampling valve is less than 350 kPa (50 psi).	Perform Procedure "C".
		The pressure at the outlet of the fuel transfer pump is at least 350 kPa (50 psi). The pressure at the fluid sampling valve is less than 350 kPa (50 psi).	Perform Procedure "E".
		The pressure at the outlet of the fuel transfer pump is at least 350 kPa (50 psi). The pressure at the fluid sampling valve is at least 350 kPa (50 psi).	Perform Procedure "J".
			Perform Procedure "J".

Expected Result:

The appropriate procedure is determined.

Results:

The appropriate procedure is determined. - Proceed to the appropriate procedure.

Test Step 8. Procedure "A"

This procedure determines the source of the excessive air in the fuel system.

Verify that the primary fuel filter is installed correctly.

Inspect the fuel lines between the fuel tank and the inlet to the fuel transfer pump. Look for the following problems:
- Cracked lines
- Loose connections

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To avoid personal injury, always wear eye and face protection when using pressurized air.

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NOTICE

To avoid damage, do not use more than 55 kPa (8 psi) to pressurize the fuel tank.

Pressurize the fuel tank to 35 kPa (5 psi). Do not use more than 55 kPa (8 psi) in order to avoid damage to the fuel tank. Check for leaks in the fuel lines between the fuel tank and the fuel transfer pump. Repair any leaks that are found.

If the source of the air is not found, disconnect the supply line from the fuel tank and connect an external fuel supply to the inlet of the fuel transfer pump. If the problem is corrected, repair the fuel tank or the stand pipe in the fuel tank.

Expected Result:

The leak is identified and the leak is repaired.

Results:

The leak is identified and the leak is repaired. - Perform Test Step 7 again.

Test Step 9. Procedure "B"

This procedure determines the cause of low fuel pressure at the outlet of the fuel transfer pump. Accomplish this procedure by using the following technique:

Check each component in order.
Repair the component or replace the component if the component is faulty. Then, crank the engine in order to determine if the pressures are correct.

Inspect the fuel lines between the fuel tank and forward fuel manifold (15) . Check each line for restrictions and for debris.

Inspect line (30) from forward fuel manifold (15) to the inlet of the fuel transfer pump. Check the line for restrictions and for debris.

Replace 500 kPa (72 psi) pressure regulator (17) .

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Illustration 8	g01388721
Top view of the front left corner of the engine (5) Rail (7) 600 kPa (87 psi) regulator for the high-pressure fuel pump (8) High-pressure fuel pump

Replace 600 kPa (87 psi) regulator (7) .

Replace fuel transfer pump (9) .

Expected Result:

The faulty component was identified. Both fuel pressures are at least 50 kPa (7 psi).

Results:

The faulty component was identified. Both fuel pressures are at least 50 kPa (7 psi). - Crank the engine. If the engine does not start, proceed to Test Step 13. If the engine starts, proceed to Test Step 16.

Test Step 10. Procedure "C"

This procedure determines the cause of low fuel pressure at the outlet of the fuel transfer pump. Accomplish this procedure by using the following technique:

Check each component in order.
Repair the component or replace the component if the component is faulty. Then, run the engine in order to determine if the pressures are correct.

Inspect the fuel lines between the fuel tank and forward manifold (15) . Check each line for restrictions and for debris.

Inspect line (30) from the forward manifold to the inlet of the fuel transfer pump. Check the line for restrictions and for debris.

Replace 500 kPa (72 psi) pressure regulator (17) .

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Illustration 9	g01388721
Top view of the front left corner of the engine (5) Rail (7) 600 kPa (87 psi) regulator for the high-pressure fuel pump (8) High-pressure fuel pump

Replace 600 kPa (87 psi) regulator (7) .

Replace fuel transfer pump (9) .

Expected Result:

The faulty component was identified. Both fuel pressures are at least 350 kPa (50 psi).

Results:

The faulty component was identified. Both fuel pressures are at least 350 kPa (50 psi). - Proceed to Test Step 16.

Test Step 11. Procedure "D"

This procedure determines the cause of low fuel pressure at the inlet to the high-pressure fuel pump. Accomplish this procedure by using the following technique:

Check each component in order.
Repair the component or replace the component if the component is faulty. Then, crank the engine in order to determine if the pressures are correct.

Remove hand priming pump (13) (if equipped). Carefully inspect the pump components for debris. Replace parts, if necessary.

Replace backflow check valve (12) .

Replace 500 kPa (72 psi) pressure regulator (17) .

Replace fuel enable valve (18) .

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Illustration 10	g01388721
Top view of the front left corner of the engine (5) Rail (7) 600 kPa (87 psi) regulator for the high-pressure fuel pump (8) High-pressure fuel pump

Replace 600 kPa (87 psi) regulator (7) .

Expected Result:

The faulty component was identified. Both fuel pressures are at least 50 kPa (7 psi).

Results:

The faulty component was identified. Both fuel pressures are at least 50 kPa (7 psi). - If the engine does not start, proceed to Test Step 13. If the engine starts, proceed to Test Step 16.

Test Step 12. Procedure "E"

This procedure determines the cause of low fuel pressure at the inlet to the high-pressure fuel pump. Accomplish this procedure by using the following technique:

Check each component in order.
Repair the component or replace the component if the component is faulty. Then, run the engine in order to determine if the pressures are correct.

Remove hand priming pump (13) (if equipped). Carefully inspect the pump components for debris. Replace parts, if necessary.

Replace backflow check valve (12) .

Replace 500 kPa (72 psi) pressure regulator (17) .

Replace fuel enable valve (18) .

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Illustration 11	g01388721
Top view of the front left corner of the engine (5) Rail (7) 600 kPa (87 psi) regulator for the high-pressure fuel pump (8) High-pressure fuel pump

Replace 600 kPa (87 psi) regulator (7) .

Expected Result:

The faulty component was identified. Both fuel pressures are at least 350 kPa (50 psi).

Results:

The faulty component was identified. Both fuel pressures are at least 350 kPa (50 psi). - Proceed to Test Step 16.

Test Step 13. Procedure "F"

This procedure is performed when the engine does not start and the low-pressure fuel system has adequate fuel pressure for starting the engine.

Observe "Status Group #2" on Cat ET. Monitor the following parameters:
- Engine Speed
- Fuel Rail Pressure
Note: The engine cranking speed must be at least 150 rpm in order to get a valid fuel rail pressure.

Crank the engine. Determine the row in Table 2 that applies to the fuel rail pressure.

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Table 2
Fuel Rail Pressure
Condition			Action
The fuel rail pressure is between 0 MPa (0 psi) and 10 MPa (1450 psi).			Perform Procedure "H".
The fuel rail pressure is 10 MPa (1450 psi) or higher.			Perform Procedure "G".

Expected Result:

The appropriate procedure is determined.

Results:

The appropriate procedure is determined. - Perform the appropriate procedure.

Test Step 14. Procedure "G"

This procedure checks the high-pressure pump when the rail pressure is 10 MPa (1450 psi) or higher and the engine does not start.

The high-pressure fuel pump has two sides. This procedure checks the pumping capacity of each side.

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Illustration 12	g01444266
Harness connectors for the high-pressure fuel pump (45) Harness connector for side 1 (46) Harness connector for side 2

Refer to Illustration 12. Unplug the harness connector for side 1 (45) .

Crank the engine for 10 seconds. Record the rail pressure.

Connect the harness connector for side 1 (45) . Unplug the harness connector for side 2 (46) .

Crank the engine for 10 seconds. Record the rail pressure.

Connect the harness connector for side 2 (46) .

Record the rail pressures in Table 3. Put the higher rail pressure in the left column. Put the lower rail pressure in the right column. Perform the steps in the Table.

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Table 3
Testing the Sides of the High Pressure Fuel Pump
	Higher Rail Pressure	Lower Rail Pressure
Step 1 Record the rail pressures.
Step 2 Multiply the higher rail pressure by 0.7.		N/A
If the lower rail pressure is greater than the value in Step 2, the high-pressure fuel pump passes this test.

Refer to the following example. In this example, the pump failed the test. The lower rail pressure is too low.

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Table 4
Example of Testing the Sides of the High Pressure Fuel Pump
	Higher Rail Pressure	Lower Rail Pressure
Step 1 Record the rail pressures.	16 MPa (2300 psi)	10 MPa (1450 psi)
Step 2 Multiply the higher rail pressure by 0.7.	11 MPa (1600 psi)	N/A
If the lower rail pressure is greater than the value in Step 2, the high-pressure fuel pump passes this test.

Expected Result:

The high-pressure fuel pump passes the test.

Results:

The high-pressure fuel pump passes the test. - Proceed to Test Step 15.
The high-pressure fuel pump failed the test. -
Repair: Perform the following procedure:
1. Replace the high-pressure fuel pump. Be sure to time the pump correctly.
1. Crank the engine.
If the engine starts, proceed to Test Step 16. If the engine does not start, proceed to Test Step 7.

Test Step 15. Procedure "H"

This procedure checks the rate of return fuel flow from the cylinder head. The rate of return fuel flow must be OK in order for the engine to start. The rate of return fuel flow is measured while the engine is cranked for 15 seconds. There are two possible failure modes:

Low Rate of Return Fuel Flow - This condition occurs when the injectors are not being supplied with a sufficient quantity of fuel from the rail. A failed pressure relief valve or a failed high-pressure fuel pump can cause this condition.

High Rate of Return Fuel Flow - The injectors are being supplied with a sufficient quantity of fuel from the rail. However, at least one injector has a high rate of return fuel flow.

This procedure determines the components that are causing the rate of return flow to be incorrect.

The rate of return flow from the cylinder head must be checked at the outlet of the 550 kPa (80 psi) regulator. There are two possible locations for the regulator. Refer to Illustration 13.

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Illustration 13	g01400037
Possible configurations for the 550 kPa (80 psi) regulator

Perform the following procedure in order to configure the engine for the test:
- Remove the drain line between the regulator and the fitting on the manifold.
- Install a cap onto the fitting on the manifold.
- Connect one end of a flexible hose to the outlet of the regulator.
- Allow the other end of the flexible hose to drain into a graduated container.

Crank the engine for 15 seconds. Determine the quantity of fuel in the graduated container.
1. If the quantity of fuel is less than 30 mL (1.0 oz), the rate of return fuel flow is too low. Replace the pressure relief valve. Configure Cat ET to view the "Fuel Rail Pressure". The parameter is in status group 2. Crank the engine. Check the rail pressure while the engine is cranking. If the rail pressure is less than 35 MPa (5000 psi), replace the high-pressure fuel pump. Crank the engine after the pump has been replaced.
  If the engine starts, refer to "Procedure "G"" in order to finish checking the fuel system. If the engine does not start, replace all of the fuel injectors.
1. If the quantity of fuel is 30 mL (1.0 oz) or more, then there is a problem with the injectors. Replace all of the fuel injectors.

Expected Result:

There was a problem with the rate of return fuel flow from the cylinder head.

Results:

There was a problem with the rate of return fuel flow from the cylinder head. - The faulty component was replaced. Install the drain line. Then, proceed to Test Step 16 in order to continue checking the fuel system.

Test Step 16. Procedure "J"

This procedure is performed when the engine starts and the low-pressure fuel system is OK.

An intermittent electrical connection at the fuel rail pressure sensor can cause the diagnostic tests on Cat ET to give incorrect results. Therefore, the electrical connections at the fuel rail pressure sensor must be checked prior to performing the diagnostic tests. The "Active Wiggle Test" is the best way to determine the condition of the sensor electrical connections.

Turn on the "Active Wiggle Test" by selecting the following menu options:
- "Diagnostics"
- "Diagnostic Tests"
- "Wiggle Test"

Start the test. Any new fault codes will be indicated in red.

Monitor the screen while you wiggle each wire at the sensor connector. Also, perform a 10 lbs pull test on each wire.

Expected Result:

There was not a new diagnostic code for fuel pressure during the test. The wiring is OK.

Results:

The wiring is OK - Proceed to the next test step.
The wiring is not OK -
Repair: Repair the wiring. Replace parts, if necessary.
Proceed to the next test step when the wiring is OK.

Test Step 17. Perform the "Fuel System Functional Test"

Perform the "Fuel System Functional Test". Continue to the next test step if the test is successful. If the test fails, Cat ET will display an error message that indicates the problem. Follow the repair procedure for the error message:
"Fuel Pump Not Timed Correctly" - Remove the high-pressure fuel pump and install the high-pressure fuel pump. Then, run the "Fuel System Functional Test" in order to verify that the problem is resolved. Proceed to the next test step once the "Fuel System Functional Test" runs successfully.
"Fuel Pump Flow Too Low" - Replace the pressure relief valve. Then, run the "Fuel System Functional Test" in order to verify that the problem is resolved. Replace the high-pressure fuel pump if the previous repair did not solve the problem. Then, run the "Fuel System Functional Test" again in order to verify that the problem is resolved. Proceed to the next test step once the "Fuel System Functional Test" runs successfully.
"Fuel Rail Low Pressure Decay Too High" - Perform Procedure "H". Then, run the "Fuel System Functional Test" in order to verify that the problem is resolved. Proceed to the next test step once the "Fuel System Functional Test" runs successfully.
"Fuel Rail High Pressure Decay Too High" - Replace the pressure relief valve. Then, run the "Fuel System Functional Test" in order to verify that the problem is resolved. If the problem is not resolved, perform Procedure "H". Proceed to the next test step once the "Fuel System Functional Test" runs successfully.
"Load Too High or ECM Not Responding" - Perform Procedure "G". Then, run the "Fuel System Functional Test" in order to verify that the problem is resolved.

Expected Result:

The "Fuel System Functional Test" runs successfully.

Results:

The "Fuel System Functional Test" runs successfully. - Proceed to Test Step 18.

Test Step 18. Check the Pressure of the Fuel in the Cylinder Head, If Necessary

Incorrect fuel pressure inside the cylinder head can cause a performance problem. This procedure checks the fuel pressure inside the cylinder head.

If you are troubleshooting one of the following performance complaints, perform this test step. If you are not troubleshooting one of the following performance complaints, continue to the next test step.

"Acceleration is Poor or Throttle Response is Poor"
"Engine Misfires, Runs Rough or Is Unstable"
"Engine Shutdown Is Intermittent"
"Engine Top Speed Is Not Obtained"
"Vehicle Top Speed is Not Obtained"

If the engine is running, stop the engine.

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Illustration 14	g01400209
Locations of the ports for measuring the fuel pressure in the cylinder head

Refer to Illustration 14. The C7 cylinder head has three ports. The C9 cylinder head has two ports. Select an unused port. Do not remove the 550 kPa (80 psi) regulator from the cylinder head. The regulator must remain installed on the engine in order for this procedure to work correctly.

Note: The plug contains an O-ring seal. Be sure to retain the seal.

Remove the plug from the selected port.

Note: Use a pressure gauge that can indicate at least 2050 kPa (300 psi). Leave both gauges connected to the engine, when possible. If a pressure gauge must be removed from the engine in order to check the fuel pressure in the cylinder head, use the pressure gauge from the fluid sampling port.

Connect a pressure gauge to the port.

Start the engine. Observe the pressure on the gauge that is connected to the cylinder head.

Expected Result:

The fuel pressure in the cylinder head is at least 400 kPa (60 psi).

Results:

The fuel pressure in the cylinder head is at least 400 kPa (60 psi). - Proceed to the next test step.
The fuel pressure in the cylinder head is less than 400 kPa (60 psi). -
Repair: Replace 550 kPa (80 psi) regulator (2) . Check the fuel pressure in the cylinder head again.
Proceed to the next test step when the fuel pressure in the cylinder head is at least 400 kPa (60 psi).

Test Step 19. Check the Injectors

There are three tests for the injectors. The tests must be performed according to the following procedure.
1. Perform the "Fuel System Verification Test".
  - Continue to the next test if all of the injectors pass the test.
  - If an injector fails the test, verify that the injector trim file is correct for the injector. Replace the injector if the injector trim file is correct and the injector fails the test. Then, perform the "Fuel System Verification Test". This will clear the active diagnostic code for the new injector.
1. Perform the "Injector Delivery Test". Replace any injectors that fail the test. If an injector is replaced, perform the "Fuel System Verification Test" in order for the ECM to determine the adaptive trim for the new injector.
1. Perform the "Cylinder Cutout Test". Replace any injectors that fail the test. If an injector is replaced, perform the "Fuel System Verification Test". This will clear the active diagnostic code for the new injector.

Expected Result:

All of the injectors pass the tests.

Results:

All of the injectors pass the tests. - Proceed to Test Step 20.

Test Step 20. Use Cat ET to Perform the "CRS Ignition Test"

This test step verifies that the low-pressure fuel system and the high-pressure fuel system work correctly during an active regeneration.

Use Cat ET to perform the "CRS Ignition Test". This test runs for approximately 5 minutes.

Note: The ECM performs several system checks at the beginning of the "CRS Ignition Test". The checks run for approximately 30 seconds. Then, the ECM enables fuel flow to the ARD. Therefore, wait for at least 30 seconds after the test is initiated before checking the fuel pressure at the outlet of the fuel transfer pump.

Monitor the fuel pressure at the outlet of the fuel transfer pump at least 30 seconds after the "CRS Ignition Test" is started.

Expected Result:

The fuel pressure at the outlet of the fuel transfer pump is at least 1600 kPa (230 psi) at least 30 seconds after the test starts.

Results:

Yes - The fuel pressure at the outlet of the fuel transfer pump is at least 1600 kPa (230 psi) at least 30 seconds after the test starts.
Repair: Perform the following procedure:
1. Turn off the engine.
1. Remove all of the tooling from the engine.
1. Verify that the O-ring seal for the cylinder head plug is not damaged. Then, install the plug into the cylinder head.
1. Install line (39) .
1. Crank the engine. Check the following locations for leaks after the engine starts:
  - Plug in the cylinder head
  - Both fittings on line (39)
  Correct any leaks. The fuel system is working correctly.
STOP
No - The fuel pressure at the outlet of the fuel transfer pump was less than 1600 kPa (230 psi) at least 30 seconds after the test starts. There is a problem with the fuel system when the ARD is operating.
Repair: Perform the following procedure:
1. Replace regulator (16) . Then, run the "ARD Ignition Test" in order to determine whether the fuel pressure at the outlet of the fuel transfer pump is at least 1600 kPa (230 psi) at least 30 seconds after the test starts. Continue to the next component if the problem is not resolved.
1. Replace fuel transfer pump (9) . Then, run the "ARD Ignition Test" in order to determine whether the fuel pressure at the outlet of the fuel transfer pump is at least 1600 kPa (230 psi) at least 30 seconds after the test starts. Continue to the next component if the problem is not resolved.
1. Replace fuel enable valve (18) . Then, run the "CRS Ignition Test" in order to verify that the fuel pressure at the outlet of the fuel transfer pump is at least 1600 kPa (230 psi) at least 30 seconds after the test starts.
  The fuel system is working correctly.
STOP