Circuit Description
When the ignition is turned ON, the engine control module (ECM) supplies power to the in-tank fuel pump, by energizing the fuel pump relay. The in-tank fuel pump remains ON as long as the engine is cranking or running and the ECM receives crankshaft reference pulses. If there are no reference pulses, the ECM turns the in-tank fuel pump OFF, 2 seconds after the ignition switch is turned ON or 2 seconds after the engine stops running. The electric fuel pump is incorporated into the modular fuel pump and sender assembly design and is located inside the fuel tank. The fuel pump supplies fuel through a fuel filter, also located in the modular fuel pump and sender assembly, through the fuel feed pipes, to the fuel rail assembly. The fuel pump provides fuel at a pressure above the pressure needed by the fuel injectors. The fuel pressure regulator, located in the modular fuel pump and sender assembly, keeps the fuel available to the fuel injectors at a regulated pressure. When the fuel pressure rises above the pressure regulator calibration, the pressure is relieved, with excess fuel exhausted into the modular fuel pump and sender assembly reservoir.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
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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.
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This step determines whether the fuel pump can provide fuel within the correct regulated pressure range.
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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.
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This step tests for a restriction in the fuel system.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views | ||||||||
Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | ||||||
2 |
Important: Inspect the fuel system for damage, or external leaks, before proceeding with this diagnostic.
Does the fuel pump operate? | -- | Go to Step 3 | |||||
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Important: Verify there is adequate fuel in the fuel tank before proceeding with this diagnostic.
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. Important:
Is the fuel pressure within the specified value? | 380-427 kPa (55-62) psi) | Go to Step 4 | Go to Step 8 | |||||
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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 |
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 |
Do any of the scan tool parameters indicate a lean condition? | -- | Go to Step 9 | |||||
7 |
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 | ||||
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 |
Did you complete the replacement? | -- | Go to Step 14 | -- | ||||
13 | Replace the modular fuel sender assembly. Refer to Fuel Pump 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 | ||||
