When the ignition switch is turned ON, the Powertrain Control Module
(PCM) will turn ON the in-tank fuel pump. The in-tank fuel pump will remain
ON as long as the engine is cranking or running and the PCM is receiving reference
pulses. If there are no reference pulses, the PCM will turn the in-tank fuel
pump OFF 2 seconds after the ignition switch is turned ON or 2 seconds after
the engine stops running. The in-tank fuel pump is an electric pump within
an integral reservoir. The in-tank fuel pump supplies fuel through the fuel
feed pipe, and in-line fuel filter to the Fuel Rail Assembly. The fuel pump
is designed to provide 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. The fuel pressure
gauge J 34730-1A
and fuel
pipe shut off adapters J 37287
are used for fuel system diagnosis.
Number(s) below refer to the step number(s) on the Diagnostic Table.
Step
| Action
| Value(s)
| Yes
| No
|
1
| Was the Powertrain On-Board
Diagnostic (OBD) System Check performed?
| --
|
Go to Step 2
| Go to
Powertrain On Board Diagnostic (OBD) System Check
|
2
|
- Turn the ignition OFF.
- Turn the air conditioning system OFF.
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.
- Install the J 34730-1A
fuel
pressure gage.
- Place the bleed hose of the fuel pressure gauge into an approved
gasoline container.
- Turn the ignition ON.
- Bleed the air out of the fuel pressure gage into an approved gasoline
container.
- Turn the ignition OFF for 10 seconds.
- Turn the ignition ON.
Important:: The fuel pump will run for approximately 2 seconds. Cycle the
ignition as necessary in order to achieve the highest possible fuel level
- Observe the fuel pressure indicated by the fuel pressure gage
with the fuel pump running.
Is the fuel pressure within the specified limits?
| 333-376 kPa (48-55 psi)
|
Go to Step 3
|
Go to Step 12
|
3
|
Important: The fuel pressure may vary slightly when the fuel pump stops running,
the fuel pressure should stabilize and remain constant.
Note the fuel pressure after the fuel pump stops running.
Does the fuel pressure drop more than the specified value in 10 minutes?
| 34 kPa (5 psi)
|
Go to Step 10
|
Go to Step 4
|
4
| Relieve the fuel pressure to the specified value.
Does the fuel pressure drop more than the specified value in 10 minutes?
| 69 kPa (10 psi)
14 kPa (2 psi)
|
Go to Step 19
|
Go to Step 5
|
5
| Is the fuel pressure suspected of dropping-off during acceleration,
cruise, or hard cornering.
| --
|
Go to Step 6
|
Go to Step 8
|
6
| Visually and physically inspect the following items for a restriction:
| • | The in-line fuel filter. |
Was a restriction found?
| --
|
Go to Step 24
|
Go to Step 7
|
7
|
- Remove the modular sender assembly. Refer to
Fuel Sender Assembly Replacement
- Visually and physically inspect the following items:
| • | The fuel pump strainer for a restriction. |
| • | The fuel pump strainer for correct position, and installation
on the fuel sender assembly |
| • | The fuel pump flex pipe for leaks. |
| • | Verify the fuel pump is the correct fuel pump for this vehicle. |
Was a problem found in any of these areas?
| --
|
Go to Step 24
|
Go to Step 19
|
8
|
- Turn the ignition OFF for 10 seconds.
- Turn the ignition ON.
Important:: The fuel pump will run for approximately 2 seconds. Cycle the
ignition as necessary in order to achieve the highest possible fuel level.
Note this pressure.
- Start the engine.
- Allow the engine to idle at normal operating temperature.
Is the fuel pressure less than the noted fuel pressure by the amount
specified?
| 21-69 kPa
(3-10 psi)
| Go to Symptoms
|
Go to Step 9
|
9
|
- Disconnect the vacuum hose from the fuel pressure regulator.
- With the engine idling, apply 12-14 inches of vacuum to the fuel
pressure regulator.
Does the fuel pressure drop by the amount specified?
| 21-69 kPa (3-10 psi)
|
Go to Step 20
|
Go to Step 21
|
10
|
- Relieve the fuel pressure. Refer to
Fuel Pressure Relief
- Disconnect the fuel feed pipe and the fuel return pipe from the
fuel rail. Refer to
Servicing Quick Connect Fittings
- Install the J 37287
fuel pipe shut-off adapters between the fuel feed pipe and the fuel
return pipe and the fuel rail.
Notice: Do not allow the fuel pressure to exceed 450 kPa (65 psi).
Fuel pressure in excess of 450 kPa (65 psi) may damage the Fuel
Pressure Regulator.
- Open the valves on the Fuel Pipe Shut-Off Adapters.
- Turn the Ignition OFF.
Pressurize the fuel system by using a scan tool.
- Place the bleed hose of the fuel pressure gauge into an approved
gasoline container.
- Bleed the air out of the fuel pressure gauge.
- Wait for the fuel pressure to build.
- Close the valve in the fuel pipe shut-off adapter that is connected
to the fuel feed pipe.
Does the fuel pressure remain constant?
| --
|
Go to Step 19
|
Go to Step 11
|
11
|
- Open the valve in the fuel pipe shut-off adapter that is connected
to the fuel feed pipe.
- Pressurize the fuel system by using a scan tool.
- Wait for the fuel pressure to build.
- Close the valve in the fuel pipe shut-off adapter that is connected
to the fuel return pipe.
Does the fuel pressure remain constant?
| --
|
Go to Step 21
|
Go to Step 22
|
12
| Is the fuel pressure above the specified limit?
| 376 kPa (55 psi)
|
Go to Step 13
|
Go to Step 15
|
13
|
- Relieve the fuel pressure. Refer to
Fuel Pressure Relief
- Disconnect the fuel return pipe from the fuel rail. Refer to
Servicing Quick Connect Fittings
- Attach a length of flexible fuel hose to the fuel rail return
outlet passage
- Place the open end of the flexible hose into an approved gasoline
container.
- Turn the ignition OFF for approximately 10 seconds.
- Turn the ignition ON.
- Observe the fuel pressure gage with the fuel pump running.
Is the fuel pressure within the specified limits?
| 333-376 kPa (48-55 psi)
|
Go to Step 23
|
Go to Step 14
|
14
| Visually and physically inspect the fuel rail outlet passages for a restriction.
Was a restriction found?
| --
|
Go to Step 24
|
Go to Step 21
|
15
| Is the fuel pressure above
the specified value?
| 0 kPa (0 psi)
|
Go to Step 16
|
Go to Step 17
|
16
|
- Relieve the fuel pressure. Refer to
Fuel Pressure Relief
- Disconnect the fuel return pipe from the fuel rail. Refer to
Servicing Quick Connect Fittings
- Install theJ 37287
fuel pipe shut-off adapter between the fuel return pipe and the fuel
rail.
- Open the valve on the fuel pipe shut-off adapter.
- Turn the ignition OFF.
- Pressurize the fuel system by using a scan tool.
Notice: Do not allow the fuel pressure to exceed 450 kPa (65 psi).
Fuel pressure in excess of 450 kPa (65 psi) may damage the Fuel
Pressure Regulator.
- Place the bleed hose of the fuel pressure gauge into an approved
gasoline container.
- Bleed the air out of the fuel pressure gauge.
- Slowly close the valve in the Fuel Pipe Shut-Off Adapter that
is connected to the Fuel Return Pipe.
Does the fuel pressure rise above the specified value?
| 333-376 kPa (48-55 psi)
|
Go to Step 21
|
Go to Step 7
|
17
| Perform Fuel System Electrical Test. Refer to
Fuel Pump Electrical Circuit Diagnosis
or
Fuel Pump Electrical Circuit Diagnosis
Was a problem found with the fuel pump electrical circuit?
| --
|
Go to Step 24
|
Go to Step 18
|
18
| Visually and physically inspect
the following items:
| • | The in-line fuel filter for obstructions. |
| • | The fuel feed pipe for a restriction. |
| • | The fuel pump strainer for obstructions. |
| • | The fuel pump flex pipe for leaks. |
Important: It will be necessary to remove the fuel sender assembly in order to
inspect the fuel pump strainer and the fuel pump flex pipe. Refer to
Fuel Sender Assembly Replacement
Was a problem found in any of these areas?
| --
|
Go to Step 24
|
Go to Step 19
|
19
| Replace the modular fuel sender assembly.
Is the action complete?
| --
|
Go to Step 25
| --
|
20
| Locate and repair the loss of vacuum to the
fuel pressure regulator.
Is the action complete?
| --
|
Go to Step 25
| --
|
21
| Replace the fuel pressure regulator.
Is the action complete?
| --
|
Go to Step 25
| --
|
22
| Locate and replace any leaking fuel injector(s).
Is the action complete?
| --
|
Go to Step 25
| --
|
23
| Locate and correct the restriction in the
fuel return pipe.
Is the action complete?
| --
|
Go to Step 25
| --
|
24
| Repair the problem as necessary.
Is the action complete?
| --
|
Go to Step 25
| --
|
25
|
- Turn the ignition OFF.
- Turn the air conditioning system OFF.
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.
- Install the J 34730-1A
fuel
pressure gage.
- Place the bleed hose of the fuel pressure gauge into an approved
gasoline container.
- Turn the ignition ON.
- Bleed the air out of the fuel pressure gage into an approved gasoline
container.
- Turn the ignition OFF for 10 seconds.
- Turn the ignition ON.
Important:: The fuel pump will run for approximately 2 seconds. Cycle the
ignition as necessary in order to achieve the highest possible fuel level
- Observe the fuel pressure indicated by the fuel pressure gage with the
fuel pump running.
Is the fuel pressure within the specified limits?
| 333-376 kPa
(48-55 psi)
|
Go to Step26
|
Go to Step11
|
26
|
Important: The fuel pressure may vary slightly when the fuel pump stops running,
the fuel pressure should stabilize and remain constant.
- Note the fuel pressure after the fuel pump stops running.
- Does the fuel pressure drop more than the specified value in 10
minutes?
| 34 kPa
(5 psi)
|
Go to Step10
| System OK
|
