Kia Optima: Fuel Pressure Test
| 1. |
Release the residual pressure in fuel line (Refer
to “Release Residual Pressure in Fuel Line” in this group).
|
When removing the fuel pump relay, a Diagnostic
Trouble Code (DTC) may occur. Delete the code with the GDS after
completion of “Release Residual Pressure in Fuel Line” work. |
|
| 2. |
Install the Special Service Tool (SST).
| (1) |
Disconnect the fuel feed tube from the high
pressure fuel pump.
|
There may be some residual pressure
even after “Release Residual Pressure in Fuel Line”
work, so cover the hose connection with a shop towel
to prevent residual fuel from spilling out before disconnecting
any fuel connection. |
|
| (2) |
Install the special service tool for measuring
the fuel pressure in between the fuel feed tube and the high
pressure fuel pump (Refer to the figure below). 
|
|
| 3. |
Inspect fuel leakage on connections among the fuel
feed tube, the high pressure fuel pump, and the SST components with
IG ON. |
| 4. |
Measure Fuel Pressure.
| (1) |
Start the engine and measure the fuel pressure
at idle.
Fuel Pressure: 495 ~ 505 kPa (5.1 ~ 5.2 kgf/cm²,
71.8 ~ 73.2 psi)
|
|
If the fuel pressure differs from
the standard value, repair or replace the related part
(Refer to the table below). |
Fuel
Pressure
|
Cause
|
Related Part
|
Too Low
|
Fuel filter clogged
|
Fuel Filter
|
Fuel leakage
|
Fuel Pressure Regulator
|
Too High
|
Fuel pressure regulator stuck
|
Fuel Pressure Regulator
|
|
| (2) |
Stop the engine, and then check for the change
in the fuel pressure gauge reading.
Standard Value: The gauge reading should hold for
about 5 minutes after the engine stops
|
|
If the gauge reading should not be
held, repair or replace the related part (Refer to the
table below). |
Fuel Pressure
(After Engine Stops)
|
Cause
|
Related
Part
|
Fuel Pressure Drops Slowly
|
Leakage on injector
|
Injector
|
Fuel Pressure Drops Immediately
|
Check valve of fuel pump stuck open
|
Fuel Pump
|
|
| (3) |
Turn the ignition switch OFF. |
|
| 5. |
Release the residual pressure in fuel line (Refer
to “Release Residual Pressure in Fuel Line”).
|
When removing the fuel pump relay, a Diagnostic
Trouble Code (DTC) may occur. Delete the code with the GDS after
completion of “Release Residual Pressure in Fuel Line” work. |
|
| 6. |
Test End
| (1) |
Remove the Special Service Tool (SST) from
the fuel feed tube and the high pressure fuel pump. |
| (2) |
Connect the fuel feed tube and the high pressure
fuel pump. |
|
Whenever the high pressure fuel pump, fuel pipe,
delivery pipe, or injector is removed immediately after shutting off
the engine, an ...
See also:
Removal
Refer to "High Pressure Fuel Pump" in this group.
...
Fuel requirements
Your new Kia vehicle is designed to use only unleaded fuel having a pump octane
number ((R+M)/2) of 87 (Research Octane Number 91) or higher.
Your new vehicle is designed to obtain maximum performa ...
Repair procedures
If the there is lack of power, excessive oil consumption or poor fuel economy,
measure the compression pressure.
1.
W ...
Release Residual Pressure in Fuel Line