SERVICE MANUAL
  Applies to: Hyundai Coupe/Tiburon 1998-2000
GROUP
Fuel System Fuel Delivery System
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FUEL PRESSURE TEST 
CAUTION
Safety glasses must be worn when performing the service as follows.
  1. 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.
  1. The fuel filter is located in the left side of the rear quarter of the engine compartment.

  1. Remove the single tie-wrap that secures the fuel pressure line to the fuel return line.

  1. Remove the electrical connector from the master cylinder reservoir below.

CAUTION
Before proceeding to next step, place shop rag over fuel filter to capture fuel spray.
  1. Move shop rag enough to expose bolt on top of fuel filter, remove bolt and line from filter.

  1. Using the fuel pressure gauge, gauge connector & gauge adapter (09353-24000, 29000), install the fuel-pressure gauge to the fuel filter. Tighten the bolt to the specified torque.

    TORQUE SPECIFICATION
    Fuel pressure gauge to fuel filter 25-35 Nm ( 250-350 kg·cm, 18-26 lb·ft )
  1. Connect the battery negative (-) terminal.

  1. Start engine and check for leaks. If no leaks are present, continue with fuel pressure test (at curb idle speed).

  1. Connect (Disconnected) the vacuum hose from the pressure regulator, (and plug the hose end). Measure the fuel pressure.

    Standard value
    SPECIFICATION
    Disconnected hose 300 kPa (3.06 kg/cm2, 44.37 psi)
    Connected hose Approx. 255 kPa (2.57 kg/cm2, 37 psi)
  1. If the results of the measurements made in steps (9) are not within the standard value, use the table below to determine the probable cause, and make the necessary repairs.

Condition
Probable cause
Remedy
Fuel pressure is too low
  • Clogged fuel filter
  • Replace fuel filter

  • Fuel leakage to the return side, caused by poor seating of the fuel-pressure regulator
  • Replace fuel pressure regulator

  • Low discharge pressure of the fuel pump
  • Check the in-tank fuel hose for leakage or replace the fuel pump
Fuel pressure is too high
  • Sticking fuel-pressure regulator
  • Replace fuel pressure regulator
  • Clogged or bent fuel return hose or pipe
  • 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
  • Repair or replace the vacuum hose or the nipple
  • Sticking or poor seating of the fuel pressure regulator
  • Repair or replace hose or pipe
  1. 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.

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 not working
  • Replace fuel pump
  1. Reduce the pressure in the fuel line.

  1. Disconnect the hose and the gauge.

    CAUTION
    Cover the hose connection with a shop towel to prevent splashing of fuel caused by fuel residual pressure in the fuel line.
  1. Replace the O-ring of the end of the hose.

  1. Connect the fuel hose to the delivery pipe and tighten with the specified torque.

  1. Check for fuel leakage.