Kia Optima Hybrid Owner's Manual Quiz
Engine Control System/Fuel System

Repair Procedures

In this manual: Engine Control System/Fuel System
General Information — 4Engine Mechanical System — 50Engine Electrical System — 20Emission Control System — 30Engine Control System/Fuel System — 84Automatic Transmission — 98Drive Shaft and Axle — 15Suspension System — 36Steering — 12Restraints — 50Brake System — 38Body (Interior and Exterior) — 54Body Electrical System — 233Heating, Ventilation, and Air Conditioning — 57
13steps
~78min
3/5difficulty
Done 0 of 13

Fuel Pressure Inspection

  1. Relieve the residual fuel pressure in the fuel line (refer to "Relieve Residual Fuel Pressure" in this group).
    When the fuel pump relay is removed, a diagnostic trouble code (DTC) is set. Clear the DTC with GDS after completing the "Relieve Fuel Pressure" procedure.
  2. Install the Special Service Tool (SST).
    1. Disconnect the fuel feed hose from the injection pipe.
      Some residual pressure may remain even after releasing the residual fuel pressure in the fuel line. Therefore, cover the hose connection with a shop towel to prevent fuel from spilling before disconnecting any fuel connection.
    2. Install the special service tool (SST) to measure the fuel pressure between the fuel feed hose and the fuel feed pipe (see the illustration below).
  3. Check for fuel leaks at the connections between the fuel feed hose, the injection pipe and the SST with the ignition switched ON.
  4. Measure the fuel pressure.
    1. Start the engine and measure the fuel pressure at idle. Fuel pressure: 333 ~ 353 kPa (3.4 ~ 3.6 kgf/cm², 48.3 ~ 51.2 psi)
      If the fuel pressure is out of specification, repair or replace the related part (see the table below).
      Fuel
      Pressure      		 Cause Related Part
      Too low Clogged fuel filter Fuel filter
      Fuel leakage Fuel Pressure Regulator
      Too high Fuel pressure regulator valve stuck Fuel Pressure Regulator
    2. Stop the engine, then check the fuel pressure gauge reading for changes. Specification: The gauge reading should be held for approximately 5 minutes after the engine is stopped.
      If the gauge reading is not held, repair or replace the related part (see the table below).
      Fuel Pressure
      (After Engine Stop)      		 Cause Related
      Part
      Fuel pressure drops slowly Injector leakage Injector
      Fuel pressure drops immediately Fuel pump check valve stuck open Fuel pump
    3. Turn the ignition off.
  5. Relieve the residual fuel pressure in the fuel line (Refer to "Relieve Residual Fuel Pressure in the Fuel Line").
    When the fuel pump relay is removed, a diagnostic trouble code (DTC) is set. Clear the DTC with GDS after completing the "Relieve Fuel Pressure" procedure.
  6. End of test
    1. Remove the special service tool (SST) from the fuel feed hose and the injection pipe.
    2. Connect the fuel feed hose and the injection pipe.

Release Fuel Line Residual Pressure
Some residual pressure may remain even after releasing the residual fuel pressure in the fuel line. Therefore, cover the hose connection with a shop towel to prevent fuel from spilling before disconnecting any fuel connection.
  1. Turn the ignition switch OFF and disconnect the negative (-) battery cable.
  2. Remove the fuel pump relay (A).
    When the fuel pump relay is removed, a diagnostic trouble code (DTC) is set. Clear the DTC with GDS after completing the "Relieve Fuel Pressure" procedure.
  3. Connect the battery negative (-) terminal.
  4. Start the engine and let it idle, then turn the ignition switch OFF after the engine stops on its own.
  5. Disconnect the negative (-) battery cable, then remove the fuel pump relay (A).
  6. Connect the battery negative (-) terminal.
  7. Clear the Diagnostic Trouble Code (DTC) related to the fuel pump relay using GDS.

Test yourself

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