Circuit Description
When the ignition switch is first turned on, the PCM energizes the fuel pump relay which applies power to the in-tank fuel pump. The fuel pump relay will remain on as long as the engine is running or cranking and the PCM is receiving reference pulses. If no reference pulses are present, the PCM de-energizes the fuel pump relay within 2 seconds after the ignition is turned on or the engine is stopped.
The fuel pump delivers fuel to the fuel rail and injectors, then to the fuel pressure regulator. The fuel pressure regulator controls fuel pressure by allowing excess fuel to be returned to the fuel tank.
Diagnostic Aids
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for a poor connection or damaged harness. Inspect the PCM harness and connectors for the following items:
| • | Improper mating. |
| • | Broken locks. |
| • | Improperly formed or damaged terminals. |
| • | Poor terminal to wire connections. |
| • | Damaged harnesses. |
Test Description
The numbers below refer to the step numbers on the Diagnostic Table:
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Tests the ignition feed circuit to the fuel pump relay.
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Verifies that the fuel pump feed circuit is OK between the fuel pump relay and the fuel pump, and that the fuel pump can deliver adequate pressure to the fuel rail.
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Tests the fuel pump feed circuit for a short to battery positive voltage.
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Tests whether the problem is being caused by an open in the fuel pump feed circuit or the fuel pump ground circuit.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you Perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Does the test lamp illuminate? | -- | |||
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. Does the pressure measure between the specified values. | 284-325 kPa (41-47psi) | |||
Connect a test lamp between the fuel pump feed circuit at the fuel pump relay connector and a known good ground. Does the test lamp illuminate? | -- | |||
5 | Test the fuel pump feed circuit for a short to voltage. Refer to Wiring Repairs . Did you find and correct the condition? | -- | -- | |
6 |
Did you find and correct the condition? | -- | ||
7 | Repair the open or short to ground in the fuel pump relay switch feed circuit. Refer to Wiring Repairs . Did you find and correct the condition? | -- | -- | |
Does the test lamp illuminate? | -- | |||
9 |
Did you find and correct the condition? | -- | ||
10 | Repair the open in the fuel pump ground circuit. Refer to Wiring Repairs . Did you find and correct the condition? | -- | ||
11 | Replace the fuel pump relay. Did you complete the replacement? | -- | -- | |
12 | Repair the fuel pump harness for an external open or short between the fuel pump connector and the fuel pump. Refer to Wiring Repairs . Did you find and correct the condition? | -- | ||
13 | Replace the fuel pump. Refer to Fuel Sender Assembly Replacement . Did you complete the replacement? | -- | -- | |
14 |
Does the fuel pressure measure between the specified values? | 284-325 kPa (41-47 psi) | System OK |
