The control module enables the fuel pump relay when the ignition switch is turned ON. The control module will disable the fuel pump relay within 2 seconds unless the control module detects ignition reference pulses. The control module continues to enable the fuel pump relay as long as ignition reference pulses are detected. The control module disables the fuel pump relay within 2 seconds if ignition reference pulses cease to be detected and the ignition remains ON.
The fuel tank stores the fuel supply. The electric fuel pump attached to the primary fuel tank module, supplies fuel through an in-line fuel filter to the fuel injection system. The fuel pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pressure regulator, a part of the secondary fuel tank module, maintains the correct fuel pressure to the fuel injection system. A fuel return pipe attaches between the in-line fuel filter and the secondary fuel tank module. When the fuel pressure exceeds the set point of the fuel pressure regulator, excess fuel flows to the low-pressure siphon jet pump on the secondary fuel tank module. The return fuel creates a venturi action inside the siphon jet pump. The venturi action causes the fuel to be drawn from the secondary side of the fuel tank though the fuel transfer tube to the primary side of the fuel tank. The electric fuel pump also supplies fuel to the high-pressure siphon jet pump, which is attached to the primary fuel tank module. The high-pressure siphon jet pump supplies fuel to the reservoir of the primary fuel tank module. The fuel pressure regulator also maintains fuel pressure in the fuel return pipe, which reduces the time to prime the low-pressure siphon jet pump.
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: DO NOT start the engine. Is the fuel pressure within the specified range? | 345-414 kPa (50-60 psi) | Go to Step 4 | Go to Step 8 |
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 5 minutes. Does the fuel pressure decrease by more than the specified value? | 55 kPa (8 psi) | Go to Step 6 | Go to Step 5 |
5 |
Do the scan tool parameters indicate a lean condition? | -- | Go to Step 9 | |
6 |
Does the fuel pressure decrease by more than the specified value? | 55 kPa (8 psi) | Go to Step 7 | Go to Step 15 |
7 |
Does the fuel pressure decrease by more than the specified value? | 55 kPa (8 psi) | Go to Step 19 | Go to Step 17 |
8 | Is the fuel pressure more than the specified value? | 414 kPa (60 psi) | Go to Step 14 | Go to Step 9 |
9 |
Is the fuel pressure more than the specified value? | 379 kPa (55 psi) | Go to Step 10 | |
10 |
Is the fuel pressure more than the specified value? | 379 kPa (55 psi) | Go to Step 16 | Go to Step 11 |
11 |
Is the fuel pressure more than the specified value? | 379 kPa (55 psi) | Go to Step 18 | Go to Step 12 |
12 |
Is the fuel pressure more than the specified value? | 379 kPa (55 psi) | Go to Step 17 | Go to Step 13 |
13 | Inspect the rear fuel feed pipe on the fuel tank for damage and for a restriction. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 19 |
14 | Inspect the fuel return pipe from the fuel filter to the fuel tank for a restriction. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 17 |
15 |
Did you complete the replacement? | -- | Go to Step 20 | -- |
16 | Replace the chassis fuel feed pipe. Refer to Fuel Hose/Pipes Replacement - Chassis . Did you complete the replacement? | -- | Go to Step 20 | -- |
17 | Replace the secondary fuel tank module. Refer to Secondary Fuel Tank Module Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- |
18 | Replace the fuel filter. Refer to Fuel Filter Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- |
19 | Replace the primary fuel tank module. Refer to Primary Fuel Tank Module Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- |
20 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 3 |