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Fuel Pressure Test: Tiburon

  1. Release fuel pressure. See FUEL PRESSURE RELEASE . Locate fuel filter in left rear corner of engine compartment, below brake master cylinder. Remove quick-tie securing fuel lines together and disconnect master cylinder reservoir connector. Disconnect high-pressure fuel hose from top of fuel filter. Cover hose connection using rags to avoid spraying of fuel.
  2. Using Fuel Pressure Gauge Adapter, install fuel pressure gauge to fuel filter. See Fig 1. Tighten fuel gauge adapter bolt to 18-26 ft. lbs. (24-35 N.m). Connect negative battery cable.
  3. Using fuel pump check connector terminal, activate fuel pump and ensure no fuel leakage are present at pressure gauge or connection. See FUEL PUMP TEST . If no leaks are present, start engine and allow to idle.
  4. Disconnect vacuum hose from fuel pressure regulator, and plug hose end. Measure and record fuel pressure at idle. Reconnect vacuum hose, and again measure and record fuel pressure. See REGULATED FUEL PRESSURE (AT IDLE)  table. If measurements are not within specification, go to next step. If measurements are okay, go to step  8.
  5. If fuel pressure is less than specified, check following conditions:
    • Restricted fuel filter.
    • Fuel pressure regulator leaking fuel to fuel return side.
    • Leaking in-tank fuel pick-up hose.
    • Low fuel pump discharge pressure.

    Repair or replace as necessary. Recheck fuel pressure.

  6. If fuel pressure is greater than specified, check for sticking fuel pressure regulator. Check for a restricted or bent fuel return hose or pipe. Repair or replace fuel hose, pipe or fuel pressure regulator.
  7. If fuel pressure does not change when regulator vacuum hose is connected and disconnected, check for following conditions:
    • Restricted or damaged vacuum hose.
    • Restricted manifold vacuum port.
    • Sticking or poorly seated fuel pressure regulator valve.

    Repair or replace as necessary. Recheck fuel pressure.

  8. If fuel pressures are as specified, stop engine and check gauge for a decrease in fuel pressure. Fuel pressure should hold for approximately 5 minutes. If fuel pressure decreases slowly after engine is stopped, check for leaking injector. Replace as necessary. If fuel pressure decreases immediately after engine is stopped, check valve inside fuel pump is not working. Replace fuel pump. After repairs are completed, recheck fuel pressure.
  9. After testing is completed, release fuel pressure. See FUEL PRESSURE RELEASE . Disconnect fuel pressure gauge from adapter. Ensure hose connection is covered by shop towel to prevent fuel spray. Remove adapter bolts and adapter. Install NEW "O" ring, and reinstall fuel line with original bolts. Apply battery voltage to fuel pump check connector terminal. See Figure. Check for fuel leaks.
REGULATED FUEL PRESSURE (AT IDLE)

Application W/ Vacuum - psi (kg/cm2 ) W/O Vacuum - psi (kg/cm2 )
Accent (1.5L) & Elantra (2.0L) (1) (1)
Tiburon (2.0L) 37.0 (2.57) 44.0 (3.06)
Santa Fe (2.4L & 2.7L) Sonata (2.4L & 2.5L) & XG 300 37.0 (2.57) 46.0-49.0 (3.26-3.48)
(1) Fuel pressure regulator is mechanically controlled and is an integral part of fuel pump assembly. Regulated fuel pressure at idle should be 49.8 psi (3.5 kg/cm2 ).
Fig 1: Testing Fuel Pressure at Fuel Filter (Tiburon)
G00032288Courtesy of HYUNDAI MOTOR CO.
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