System Pressure
- 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 has threaded plug closing it. Bridge fuel pump relay with Jumper Switch (US 4480/3).
- 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 75-82 psi (5.3-5.8 kg/cm2 ). If pressure reading is low and fuel pump delivery quantity is good, replace diaphragm pressure regulator.
- 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 not correct with line open, replace diaphragm pressure regulator.