When the ignition is turned ON, the engine control module (ECM) turns ON 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 ignition reference pulses. If there are no reference pulses, the ECM turns the in-tank fuel pump OFF 2 seconds after the ignition 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, through the fuel feed pipes, and to the fuel rail assembly. The fuel pump provides fuel at a pressure above the pressure needed by the fuel injectors. A fuel pressure regulator, attached to the fuel rail, keeps the fuel available to the fuel injectors at a regulated pressure. Unused fuel is returned to the fuel tank by a separate fuel return pipe.
• | A hard start or long crank time when the engine is cold can be caused by low fuel pump volume. |
• | The fuel pressure should build quickly when the fuel pump is turned ON. |
• | If you must wait more than 2 seconds for the fuel pressure to build, suspect low fuel pump volume. |
• | For an intermittent condition, refer to Intermittent Conditions . |
Step | Action | Values | Yes | No | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 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 | |||||||||
3 |
Important: Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.
Important:
Is the fuel pressure within the specified range? | 283-345 kPa (41-50 psi) | Go to Step 4 | Go to Step 10 | ||||||||
4 |
Important: The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant. Monitor the fuel pressure gage for 1 minute. Does the fuel pressure decrease by more than the specified value? | 34 kPa (5 psi) | Go to Step 7 | Go to Step 5 | ||||||||
5 |
Does the fuel pressure decrease by more than the second specified value? | 69 kPa (10 psi) 14 kPa (2 psi) | Go to Step 20 | Go to Step 6 | ||||||||
6 |
Does the scan tool parameters indicate a lean condition? | -- | Go to Step 13 | Go to Diagnostic Aids | ||||||||
7 |
Is the fuel pressure regulator leaking fuel? | -- | Go to Step 19 | Go to Step 8 | ||||||||
8 |
Does the fuel pressure remain constant? | -- | Go to Step 16 | Go to Step 9 | ||||||||
9 |
Does the fuel pressure remain constant? | -- | Go to Step 19 | Go to Step 17 | ||||||||
10 | Is the fuel pressure more than the specified value? | 345 kPa (50 psi) | Go to Step 11 | Go to Step 13 | ||||||||
11 |
Is the fuel pressure within the specified range? | 283-345 kPa (41-50 psi) | Go to Step 18 | Go to Step 12 | ||||||||
12 | Inspect the fuel rail return pipe and the fuel rail outlet passage for a restriction. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 19 | ||||||||
13 |
Notice: DO NOT allow the fuel pressure to exceed 517 kPa (75 psi). Excessive pressure may damage the fuel system. Does the fuel pressure increase to more than the specified value? | 345 kPa (50 psi) | Go to Step 19 | Go to Step 14 | ||||||||
14 | Inspect the following components for a restriction:
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 15 | ||||||||
15 | 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 21 | Go to Step 16 | ||||||||
16 |
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 20 | ||||||||
17 |
Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||
18 | Repair the restricted fuel return pipe. Did you complete the repair? | -- | Go to Step 21 | -- | ||||||||
19 |
Important: Inspect for a missing or damaged O-ring seal before replacing the fuel pressure regulator. Replace the fuel pressure regulator. Refer to Fuel Pressure Regulator Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||
20 | Replace the fuel pump. Refer to Fuel Pump Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||
21 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 3 |