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, attached
to the Fuel Sender Assembly. The in-tank fuel pump (3) supplies fuel through
the fuel feed pipe (2), and in-line fuel filter (1) to the Fuel Rail Assembly
(6). The fuel pump is designed to provide fuel at a pressure above the pressure
needed by the fuel injectors. A fuel pressure regulator (7), 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 (4).
The fuel pressure gauge J 34730-1A
(5) and fuel pipe shut off adapters J 37287
(8) are used for fuel system diagnosis.
Number(s) below refer to the step number(s) on the Diagnostic Table.
Fuel System Pressure Test VIN K
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
|
Important: Before proceeding with this chart perform Fuel System Electrical Test.
Refer to
Fuel Pump Electrical Circuit Diagnosis
.
- 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. Refer to Fuel System Pressure Test VIN K
Illustration Associated with Test Description.
- 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 13
|
3
|
Important: The fuel pressure may vary slightly when the fuel pump stops running.
After the fuel pump stops running, the fuel pressure should stabilize and
remain constant.
- Note fuel pressure after 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 fuel pressure to the specified value.
- Monitor the fuel pressure.
Does pressure drop more than the specified value in 10 minutes?
| 69 kPa (10 psi)
14 kPa (2 psi)
|
Go to Step 20
|
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-pipe fuel filter. |
Was a restriction found?
| --
|
Go to Step 26
|
Go to Step 7
|
7
|
- Remove the fuel 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 pulse dampener 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 26
|
Go to Step 20
|
8
|
- Start the engine.
- Allow the engine to idle at normal operating temperature.
Does the fuel pressure drop 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 21
|
Go to Step 22
|
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. Refer to Fuel System Pressure Test VIN K
Illustration Associated With Circuit
Description.
- 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 11
|
Go to Step 12
|
11
|
- Remove the fuel sender assembly. Refer to
Fuel Sender Assembly Replacement
.
- Visually and physically inspect the fuel pump pulse dampener.
Is the fuel pump pulse dampener leaking?
| --
|
Go to Step 23
|
Go to Step 20
|
12
|
- 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 22
|
Go to Step 24
|
13
| Is the fuel pressure above the specified limit?
| 376 kPa (55 psi)
|
Go to Step 14
|
Go to Step 16
|
14
|
- 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 (48-55psi)
|
Go to Step 25
|
Go to Step 15
|
15
| Visually and physically
inspect the fuel rail outlet passages for a restriction.
Was a restriction found?
| --
|
Go to Step 26
|
Go to Step 22
|
16
| Is the fuel pressure above
the specified value?
| 0 kPa (0 psi)
|
Go to Step 17
|
Go to Step 18
|
17
|
- 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 the J 37287
fuel pipe shut-off adapter between the fuel return pipe and the fuel
rail. Refer to Fuel System Pressure Test VIN K
.
- Open the valve on the fuel pipe shut-off adapter.
- 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.
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.
- 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 22
|
Go to Step 7
|
18
| Perform Fuel System Electrical Test. Refer to
Fuel Pump Electrical Circuit Diagnosis
.
Was a problem found with the fuel pump electrical circuit?
| --
|
Go to Step 26
|
Go to Step 19
|
19
|
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
.
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 strainer for correct positioning and installation
on the fuel sender assembly. |
| • | The fuel pump pulse dampener for leaks. |
Was a problem found in any of these areas?
| --
|
Go to Step 26
|
Go to Step 20
|
20
| Replace the fuel pump.
Refer to
Fuel Sender Assembly Replacement
.
Is the action complete?
| --
|
Go to Step 27
| --
|
21
| Locate and repair the loss of vacuum to the
fuel pressure regulator.
Is the action complete?
| --
|
Go to Step 27
| --
|
22
| Replace the fuel pressure regulator.
Refer to
Fuel Pressure Regulator Replacement
.
Is the action complete?
| --
|
Go to Step 27
| --
|
23
| Replace the fuel pump pulse dampener.
Refer to
Fuel Sender Assembly Replacement
.
Is the action complete?
| --
|
Go to Step 27
| --
|
24
| Locate and replace any leaking fuel injector(s). Refer to
Fuel Injector Replacement
.
Is the action complete?
| --
|
Go to Step 27
| --
|
25
| Locate and correct the restriction in the
fuel return pipe.
Is the action complete?
| --
|
Go to Step 27
| --
|
26
| Repair the problem as necessary.
Is the action complete?
| --
|
Go to Step 27
| --
|
27
|
- 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. Refer to Fuel System Pressure Test VIN K
Illustration Associated with Test Description.
- 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 28
|
Go to Step 13
|
28
|
Important: The fuel pressure may vary slightly when the fuel pump stops running.
After the fuel pump stops running, the fuel pressure should stabilize and
remain constant.
- Note fuel pressure after pump stops running.
- Does the fuel pressure drop more than the specified value in
10 minutes?
| 34 kPa (5
psi)
|
Go to Step 10
| System OK
|
