Fuel Pressure Test

Reduce the internal pressure of the fuel pipes and hoses by the following procedures.
- Disconnect the fuel pump harness connector after removing the rear seat cushion.
- Start the engine and after it stalls, turn the ignition switch to the OFF position.
- Disconnect the battery negative (-) terminal.
- Connect the fuel pump harness connector.
Remove the bolt connecting the fuel line to the fuel filter.
CAUTION: Cover the hose connecting with a shop towel to prevent splashing of fuel caused by fuel residual pressure in the fuel line.
Install the special service tool (SST) for measuring the fuel pressure.
1. Disconnect the fuel feed from the delivery pipe.
  WARNING: Cover the hose connection with a shop towel to prevent splashing of fuel caused by residual pressure in the fuel line.
2. Install the Fuel Pressure Gauge Adapter (09353-38000) between the delivery pipe and the fuel feed hose.
3. Connect the Fuel Pressure Gauge Connector (09353-38000).
4. Connect the Fuel Pressure Gauge and Hose (09353-24100) to the Fuel Pressure Gauge Connector (09353-24000)
5. Connect the fuel feed hose to the Fuel Pressure Gauge Adaptor (09353-38000)
  Fuel pressure gauge to fuel delivery pipe 25~35 N.m (250~350 kg.cm, 18~26 lb.ft)
  
  Fig 1: Inspecting Fuel Delivery System Using Fuel Pressure Gauge Adapter
  Courtesy of HYUNDAI MOTOR CO.
Connect the battery's negative (-) terminal.
Apply battery voltage to the terminal for the pump drive and activate the fuel pump: then, with fuel pressure gauge or connection part.
Start and run the engine at curb idle speed.
Disconnect the vacuum hose from the pressure regulator, and plug the end of the hose. Measure the fuel pressure at idle.
Standard value :

320 ~ 340 kPa (3.26 ~ 3.47 kg/cm² , 46 ~ 49 psi)
Measure the fuel pressure when the vacuum hose is connected to the pressure regulator.
Standard value :

Approx. 255 kPa (2.57 kg/cm² , 37 psi)

If the results of the measurements made in steps 7 and 8 are not within the standard value, use FUEL SYSTEM CAUSE REMEDY CHART to determine the probable cause, and make the necessary repairs.

FUEL SYSTEM CAUSE REMEDY CHART (1 OF 2)

Condition	Probable cause	Remedy
Fuel pressure is too low	Clogged fuel filter Fuel leakage to the return side, caused by poor seating of the fuel pressure regulator	Replace fuel filter Replace fuel pressure regulator
Fuel pressure is too low	Low discharge pressure of the fuel pump	Check the in-tank fuel hose or replace the fuel pump
Fuel pressure is toot high	Sticking fuel-pressure regulator Clogged or bent fuel return hose or pipe	Replace fuel pressure regulator Repair or replace hose or pipe
There is no difference in fuel pressure when the vacuum hose is connected and when it is not.	Clogging, or damaged vacuum hose or the nipple Sticking or poor seating of the fuel pressure regulator	Repair or replace the vacuum hose or the nipple Repair or replace hose or pipe

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 table.

FUEL SYSTEM CAUSE REMEDY CHART (2 OF 2)

Condition	Probable cause	Remedy
Fuel pressure drops slowly after engine is stopped	Injector leakage	Replace injector
Fuel pressure drops immediately after engine is stopped	The check valve within the fuel pump is open	Replace fuel pump

Reduce the pressure in the fuel line.
Disconnect the hose and the gauge.
WARNING: Cover the hose connection with a shop towel to prevent splashing of fuel caused by fuel residual pressure in the fuel line.
Replace the O-ring of the end of the hose.
Connect the fuel hose to the delivery pipe and tighten with the specified.
Check for fuel leakage.