Fuel Pressure Test

Reduce the internal pressure of the fuel pipes and hoses by using the following procedures.
Disconnect the fuel pump harness connector in the rear seat side.

Fig 1: Disconnecting The Fuel Pump Harness Connector
Courtesy of KIA MOTORS AMERICA, INC.
Start the engine and, after it stops by itself, turn the ignition switch to the OFF position. Disconnect the battery negative (-) terminal. Connect the fuel pump harness connector.
Disconnect the fuel high pressure hose at the fuel line side.

Fig 2: Disconnecting The Fuel High Pressure Hose
Courtesy of KIA MOTORS AMERICA, INC.

CAUTION: Cover the pipe connection with a shop towel to prevent splashing of fuel caused by residual pressure in the fuel line.
Using the fuel pressure gauge adapter, install the fuel pressure gauge to the fuel high pressure hose.
Connect the battery's negative (-) terminal.
Apply battery voltage to the fuel pump drive terminal, activate the fuel pump; then, with fuel pressure applied, check that there is no fuel leakage from the pressure gauge or connection part.

Fig 3: Installing The Fuel Pressure Gauge
Courtesy of KIA MOTORS AMERICA, INC.
Disconnect the vacuum hose from the pressure regulator and plug the hose end. Measure the fuel pressure at idle.
Standard value: 320-340 kPa (3.26-3.47 kg/cm² , 46-49 psi)

Fig 4: Disconnecting The Vacuum Hose From The Pressure Regulator
Courtesy of KIA MOTORS AMERICA, INC.
Measure the fuel pressure when the vacuum hose is connected to the pressure regulator (while engine is running).
Standard value: Approximately 270 kPa (2.75 kg/cm² , 39 psi)

Fig 5: Measuring The Fuel Pressure
Courtesy of KIA MOTORS AMERICA, INC.
If the results of the measurements made in steps (6) and (7) are not within the standard value, use the chart below to determine the probable cause, and make the necessary repairs.

Fig 6: Running Pressure Probable Cause Chart
Courtesy of KIA MOTORS AMERICA, INC.
Stop the engine and check for a change in the fuel pressure gauge reading, which should hold for approximately 5 minutes. If the gauge indication drops, observe the rate of drop. Determine and remove the causes according to the following chart.

Fig 7: Rest Pressure Probable Cause Chart
Courtesy of KIA MOTORS AMERICA, INC.
Reduce the fuel pressure in the fuel line.
Disconnect the high pressure hose and remove the fuel pressure gauge.
CAUTION: Cover the pipe connection with a shop towel to prevent splashing of fuel caused by residual pressure in the fuel line.
Install a new O-ring at the groove in the end of the high pressure hose.
Connect the high pressure fuel hose to the delivery pipe, and tighten the screws to the specified torque.
High pressure fuel hose to delivery pipe tightening torque: 3-4 N.m 30-40 kg/cm, 2.2-3 lb-ft
Check for fuel leaks. Apply battery voltage to the fuel pump drive terminal to operate the fuel pump. With pressure, check the fuel line for leaks.