System Description
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 system is a returnless on-demand design. The fuel pressure regulator is a part of the primary fuel tank module, eliminating the need for a return pipe from the engine. A returnless fuel system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.
An electric turbine style fuel pump attaches to the primary fuel tank module inside the fuel tank. The fuel pump supplies high pressure fuel through the fuel filter, past the fuel pressure regulator, and through the fuel feed pipe to the fuel injection system. The fuel pressure regulator has a T-joint that diverts the needed fuel to the fuel rail with the unused fuel dropping back into the reservoir of the primary fuel tank module. The primary fuel tank module contains a reverse flow check valve. The check valve and the fuel pressure regulator maintain fuel pressure in the fuel feed pipe and the fuel rail in order to prevent long cranking times.
The primary fuel tank module also contains a primary jet pump and a secondary jet pump. Fuel pump flow loss, caused by vapor expulsion in the pump inlet chamber, is diverted to the primary jet pump and the secondary jet pump through a restrictive orifice located on the pump cover. The primary jet pump fills the reservoir of the primary fuel tank module. The secondary jet pump creates a venturi action which causes the fuel to be drawn from the secondary side of the fuel tank, through the fuel transfer pipe, to the primary side of the fuel tank.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | 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 7 |
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? | 100 kPa (14.5 psi) | Go to Step 6 | Go to Step 5 |
5 |
Do the scan tool parameters indicate a lean condition? | -- | Go to Step 8 | |
6 |
Does the fuel pressure decrease by more than the specified value? | 55 kPa (8 psi) | Go to Step 11 | Go to Step 9 |
7 | Is the fuel pressure more than the specified value? | 414 kPa (60 psi) | Go to Step 11 | Go to Step 8 |
8 |
Is the fuel pressure more than the specified value? | 379 kPa (55 psi) | Go to Step 10 | Go to Step 11 |
9 |
Did you complete the replacement? | -- | Go to Step 12 | -- |
10 | Replace the chassis fuel feed pipe. Refer to Fuel Hose/Pipes Replacement - Chassis . Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Replace the primary fuel tank module. Refer to Primary Fuel Tank Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
12 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 3 |
