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
| Go to
Diagnostic System Check - Engine Controls
|
2
|
Important: Inspect the fuel system for damage or external leaks before proceeding with
this diagnostic.
- Turn ON the ignition, with the engine OFF.
- Command the fuel pump relay ON with a scan tool.
Does the fuel pump operate?
| --
| Go to
Step 3
| Go to
Fuel Pump Electrical Circuit Diagnosis
|
3
|
Important: Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.
- Turn OFF the ignition.
- Turn OFF all accessories.
- Install the SA9127E
Gage Bar Set with the Fuel Pressure Adapter and the Drain Hose. Refer to
Fuel Pressure Gage Installation and Removal
.
- Turn ON the ignition, with the engine OFF.
Important: DO NOT start the engine.
- Command the fuel pump relay ON with a scan tool.
- Observe the fuel pressure gage with the fuel pump commanded ON.
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
|
- Operate the vehicle within the conditions to reproduce the original symptoms.
- Monitor the O2 and the Fuel Trim parameters with a scan tool.
Do the scan tool parameters indicate a lean condition?
| --
| Go to
Step 9
| Go to
Symptoms - Engine Controls
|
6
|
- Turn OFF the ignition.
- Relieve the fuel pressure. Refer to
Fuel Pressure Relief
.
- Remove the fuel pressure gage from the fuel pressure test connection.
- Disconnect the chassis fuel hose from the engine compartment fuel pipe.
- Connect the fuel feed hose to the inlet side of SA9127E-7
using the J 43937
3/8 inch Male Fuel Pressure Adapter Line.
- Connect the return hose from the SA9127E-7
to the outlet side of SA9127E-7
.
- Place the other end of the return hose into the fuel filler pipe.
- Close the valve on the SA9127E-7
.
- Turn ON the ignition, with the engine OFF.
- Command the fuel pump relay ON for a minimum of 10 seconds with
a scan tool.
- Record the fuel pressure.
- Command the fuel pump relay OFF.
- 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 7
| Go to
Step 15
|
7
|
- Turn OFF the ignition.
- Open the valve on the SA9127E-7
.
- Remove the SA9127E-7
.
- Connect the fuel feed hose to the engine compartment fuel pipe.
- Raise the vehicle. Refer to
Lifting and Jacking the Vehicle
in General Information.
- Disconnect the fuel feed pipe from the fuel filter inlet.
- Connect the fuel feed pipe to the inlet side of SA9127E-7
using the J 43937
3/8 inch Male Fuel Pressure Adapter Line.
- Connect the return hose from the SA9127E-7
to the outlet side of SA9127E-7
.
- Place the other end of the return hose into the fuel filler pipe.
- Open the valve on the SA9127E-7
.
- Turn ON the ignition, with the engine OFF.
- Command the fuel pump relay ON for a minimum of 10 seconds with
a scan tool.
- Close the valve on the SA9127E-7
.
- Record the fuel pressure.
- Command the fuel pump relay OFF.
- 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 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
|
- Turn OFF the ignition.
- Relieve the fuel pressure. Refer to
Fuel Pressure Relief
.
- Remove the fuel pressure gage from the fuel pressure test connection.
- Disconnect the chassis fuel hose from the engine compartment fuel pipe.
- Connect the fuel feed hose to the inlet side of SA9127E-7
using the J 43937
3/8 inch Male Fuel Pressure Adapter Line.
- Connect the return hose from the SA9127E-7
to the outlet side of SA9127E-7
.
- Place the other end of the return hose into the fuel filler pipe.
- Connect the fuel pressure gage to the SA9127E-7
.
- Open the valve on the SA9127E-7
.
- Turn ON the ignition, with the engine OFF.
- Command the fuel pump relay ON for a minimum of 10 seconds with
a scan tool.
Is the fuel pressure more than the specified value?
| 379 kPa (55 psi)
| Go to
Symptoms - Engine Controls
| Go to
Step 10
|
10
|
- Turn OFF the ignition.
- Remove the SA9127E-7
.
- Connect the chassis fuel hose to the engine compartment fuel pipe.
- Raise the vehicle. Refer to
Lifting and Jacking the Vehicle
in General Information.
- Disconnect the fuel feed pipe at the fuel filter outlet.
- Connect the inlet side of SA9127E-7
to the fuel filter outlet using the J 43937
3/8 inch Female Fuel Pressure Adapter Line.
- Place the return hose from the SA9127E-7
into the fuel filler neck.
- Open the valve on the SA9127E-7
.
- Turn ON the ignition, with the engine OFF.
- Command the fuel pump relay ON for a minimum of 10 seconds with
a scan tool.
Is the fuel pressure more than the specified value?
| 379 kPa (55 psi)
| Go to
Step 16
| Go to
Step 11
|
11
|
- Turn OFF the ignition.
- Remove the SA9127E-7
.
- Remove the return hose from the SA9127E-7
.
- Connect the chassis fuel hose to the engine compartment fuel pipe.
- Raise the vehicle. Refer to
Lifting and Jacking the Vehicle
in General Information.
- Disconnect the fuel feed and return pipes at the fuel filter inlet.
- Connect the fuel feed pipe to the inlet side of SA9127E-7
using the J 43937
3/8 inch Male Fuel Pressure Adapter Line.
- Connect the fuel return pipe to the outlet side of SA9127E-7
using the J 43937
5/16 inch Male Fuel Pressure Adapter Line.
- Open the valve on the SA9127E-7
.
- Turn ON the ignition, with the engine OFF.
- Command the fuel pump relay ON for a minimum of 10 seconds with
a scan tool.
Is the fuel pressure more than the specified value?
| 379 kPa (55 psi)
| Go to
Step 18
| Go to
Step 12
|
12
|
- Turn OFF the ignition.
- Remove the J 43937
5/16 inch Male Fuel Pressure Adapter Line from the fuel return pipe and the SA9127E-7
.
- Connect the return hose from the SA9127E-7
to the outlet side of SA9127E-7
.
- Place the other end of the return hose into the fuel filler pipe.
- Open the valve on the SA9127E-7
.
- Turn ON the ignition, with the engine OFF.
- Command the fuel pump relay ON for a minimum of 10 seconds with
a scan tool.
- Close the valve on the SA9127E-7
.
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
|
- Turn OFF the ignition.
- Open the valve on the SA9127E-7
.
- Remove the SA9127E-7
.
- Connect the chassis fuel hose to the engine compartment fuel pipe.
- Raise the fuel rail, with the fuel line connected. Refer to
Fuel Injector and Fuel Rail Replacement
.
- Turn ON the ignition, with the engine OFF.
- Command the fuel pump relay ON with a scan tool.
- Locate and replace the leaking fuel injector. Refer to
Fuel Injector and Fuel Rail Replacement
.
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
|