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Test Description

The numbers below refer to the step numbers in the diagnostic table.

  1. 1:  The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
  2. 3:  This step determines whether the fuel pump can provide fuel within the correct regulated pressure range.
  3. 4:  This step tests that the fuel system can maintain fuel pressure with the pump Off. A fuel pressure drop of more than 34 kPa (5 psi) within the specified time indicates a leak in the fuel system.
  4. 11:  This step tests for a restriction in the fuel system.
Fuel System Diagnosis

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics Fuel Hose/Pipes Routing Diagram 
Connector End View Reference:  Engine Control Module (ECM) Connector End Views  or  Engine Controls Connector End Views 
1  Did you perform the Diagnostic System Check - Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2
IMPORTANT: Inspect the fuel system for damage, or external leaks, before proceeding with this diagnostic.
  1. Turn ON the ignition, with the engine OFF.
  2. Use a scan tool in order to command the fuel pump ON.
Does the fuel pump operate?		 - Go to Step 3  Go to Fuel Pump Electrical Circuit Diagnosis 
3 
IMPORTANT: Verify there is adequate fuel in the fuel tank before proceeding with this diagnostic.
  1. Turn OFF the ignition.
  2. Turn OFF all of the accessories.
    3. CAUTION: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gage. Place the towel in an approved container when the connection of the fuel pressure gage is complete.
  3. Install the J 34730-1A  fuel pressure gage.
  4. Place the bleed hose of the fuel pressure gage into an approved gasoline container.
  5. Turn ON the ignition, with the engine OFF.
  6. Use a scan tool in order to command the fuel pump ON.
  7. Bleed the air out of the fuel pressure gage.
    8. IMPORTANT:
    • The fuel pump may need to be commanded to ON a few times in order to obtain the highest possible fuel pressure.
    • Do not start the engine.
  8. Observe the fuel pressure gage, with the fuel pump commanded ON.
Is the fuel pressure within the specified value?		 380-427 kPa (55-62) psi) Go to Step 4  Go to Step 8 
4 
IMPORTANT: The fuel pressure may vary slightly when the fuel pump stops running. After the fuel pump stops running, the fuel pressure should stabilize and remain constant.
Monitor the fuel pressure gage for 1 minute.Does the fuel pressure drop more than the specified value?		 34 kPa (5 psi) Go to Step 7  Go to Step 5 
5
  1. Relieve the fuel pressure to the first specified value.
  2. Monitor the fuel pressure gage for 1 minute.
Does the fuel drop more than the second specified value?		 69 kPa (10 psi)
14 kPa (2 psi)		 Go to Step 13  Go to Step 6 
6
  1. Operate the vehicle within the conditions of the customers concern.
  2. Use a scan tool in order to monitor the fuel related parameters.
Do any of the scan tool parameters indicate a lean condition?		 - Go to Step 9  Go to Symptoms - Engine Controls 
7
  1. Turn OFF the ignition.
  2. Relieve the fuel pressure. Refer to Fuel Pressure Relief Procedure .
  3. Disconnect the fuel feed pipe from the fuel rail.
  4. Install the J 37287  fuel pipe shut-off adapter between the fuel pipe and the fuel rail.
  5. Open the valve on the fuel feed pipe shut-off adapter.
  6. Use a scan tool in order to command the fuel pump ON.
  7. Bleed the air from the fuel pressure gage.
  8. Close the fuel feed pipe shut-off valve.
  9. Monitor the fuel pressure gage for 1 minute.
Does the fuel pressure remain constant?		 - Go to Step 13  Go to Step 12 
8 Is the fuel pressure more than the specified value? 427 kPa (62 psi) Go to Step 13  Go to Step 9 
9 Inspect the harness connectors and the ground circuits of the fuel pump for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 10 
10 Inspect the fuel feed pipe for a restriction.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 11 
11  Inspect for a restricted or plugged fuel filter. Refer to Fuel Sender Assembly Replacement .
Did you find and correct the condition?		 - Go to Step 14  Go to Step 13 
12
  1. Turn OFF the ignition.
  2. Raise the fuel rail, with the fuel lines connected. Refer to Fuel Rail Assembly Replacement .
  3. Turn ON the ignition, with the engine OFF.
  4. Command the fuel pump relay ON with a scan tool.
  5. Locate and replace the leaking fuel injector. Refer to Fuel Rail Assembly Replacement .
Did you complete the replacement?		 - Go to Step 14  -
13 Replace the modular fuel sender assembly. Refer to Fuel Sender Assembly Replacement .
Did you complete the replacement?		 - Go to Step 14  -
14 Operate the system in order to verify the repair.
Did you correct the condition?		 - System OK Go to Step 3 
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