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 is sealed by a threaded plug. 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 68-78 psi (4.7-5.4 kg/cm2 ). If pressure reading is low and fuel pump delivery quantity is good, replace 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 incorrect with line open, replace diaphragm pressure regulator.
- 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.