1987 Audi 5000 CS, StandardFACTORY OEM SERVICE PROCEDURE

System Pressure

  1. Connect Pressure Gauge (VW 1318 ) between line from fuel distributor to cold start valve and test port connection on lower chamber of fuel distributor, using Adapter Fittings (VW 1318/5 ). Test port is sealed by a threaded plug. Bridge fuel pump relay with Jumper Switch (US 4480/3 ).
  2. Disconnect wiring from differential pressure regulator. Open valve on pressure gauge (points at cold start valve line when open) and activate fuel pump. System pressure must be 68-78 psi (4.7-5.4 kg/cm2 ). If pressure reading is low and fuel pump delivery quantity is good, replace pressure regulator.
  3. If pressure reading is high, disconnect fuel tank return line from diaphragm pressure regulator. Repeat test. If reading is correct, check for plugged return line. If reading is incorrect with line open, replace diaphragm pressure regulator.
  4. If pressure is not within specification and pressure regulator valve has been replaced adjust system pressure at fuel distributor. Refer to SYSTEM PRESSURE in ADJUSTMENTS  section of this article.
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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.