1993 Audi S4 2.2 PFACTORY OEM SERVICE PROCEDURE

Fuel Pump Check Valve

  1. Ensure fuel pressure regulator, fuel pump, fuel injectors and fuel filter are OK.
  2. Ensure Feed rate of fuel pump is OK. See FUEL PUMP FEED RATE  .
  3. Make sure battery is fully charged (at least 12 volts).
  4. Remove fuse No. 17 (15-amp) from fuse holder. See Figure . Connect remote control (VW 1348/3A) using adapter lead (VW 1348/3-2) and adapter cables from (VW 1594) between fuse No. 17, terminal No. 2, and battery positive (+) terminal. On vehicles with A/C, connect clip to remote starter aid connection in engine compartment.
  5. Connect pressure gauge (VAG 1318) between fuel supply and fuel collector pipes with adapter (VAG 1318/1 1), (VAG 1318/13) and (VAG 1318/15). See Fig 1 . Lever to pressure gauge in "OPEN"position.
    Fig 1: Identifying Fuel Gauge Installation For Fuel Pump Check Valve Test
    G00177387Courtesy of AUDI OF AMERICA, INC.
  6. Operate remote control for approximately 30 seconds.
  7. Move lever on pressure gauge to "CLOSED" position.
    8. NOTE: Pressure gauge lever must remain in "CLOSED" position during measuring procedure.
  8. Briefly operate remote control until maximum 80 psi (5.6 kg/cm2 ) is indicated.
  9. Watch pressure drop. After 10 minutes, maximum pressure drop should be 7 psi (0.5 kg/cm2 ).
  10. If pressure drop is greater, carry out following checks:
    • Check pressure gauge connections for leaks
    • Check fuel lines for leaks
    If no leaks are present, fuel pump check valve is malfunctioning. Replace fuel pump.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.