Fuel Delivery and Air Induction: Testing and Inspection

SYSTEM PRESSURE
- Connect VW 1318 pressure gauge between the fuel line at the cold start valve and lower chamber test connection on the fuel distributor
- Use adapter VW 1318/5 on lower fuel chamber connection
- Remove fuel pump relay and jump socket with US 4480/3
- Remove wiring connector from differential pressure regulator
- Open valve on VW 1318 pressure gauge
- Energize fuel pump
System pressure should be 5.2 to 5.6 bar (75 to 82 PSI)

NOTE: System pressure is not adjustable.

- If system pressure is incorrect, check: Fuel pump delivery quantity. Fuel supply and return lines for restrictions. Fuel filters
- If pressure is still incorrect, replace pressure regulator and retest system pressure





DIFFERENTIAL PRESSURE (PART I)
- Close valve on VW 1318 pressure gauge (wiring connector for differential pressure regulator remains disconnected)
- Energize fuel pump: Differential pressure should be 0.2 to 0.5 bar (2.9 to 7.0 PSI) less than previously measured system pressure
- If not within specifications replace differential pressure regulator and retest
- If still not within specifications replace fuel distributor





DIFFERENTIAL PRESSURE (PART II)
- Connect adapter VW 1315 A/1 between differential pressure regulator and wiring connector
- Connect multimeter US 1119 to adapter VW 1315 A/1: Set to 200 mA scale
- Remove wiring connector from engine coolant temperature sensor





DIFFERENTIAL PRESSURE (PART II) CONTINUED
- Connect 15 kohms side of tool 1490 to temperature sensor wiring connector. Side remains disconnected.
- Turn ignition on
- Energize fuel pump: Differential pressure should be 0.7 to 1.2 bar (10 to 17.5 PSI) less than previously measured system pressure
Differential pressure regulator current should be 50 to 80 mA
- If amperage is within specifications but pressure is not within specifications, replace differential pressure regulator and recheck.
- If pressure and amperage readings are not within specifications: Check ground wire of temperature sensor at cold start valve If ground is OK, check all electrical connections If all wiring and connections are OK, replace control unit





RESIDUAL PRESSURE
- Open valve of VW 1318
- Energize fuel pump for 30 seconds
- Shut off fuel pump
- Minimum pressure after 10 minutes should be 2.6 bar (38 PSI). If pressure is too low check: External leaks, Pressure regulator, Fuel pump check valve, Sensor plate adjustment
- Remove fuel pressure gauge and reconnect fuel lines
- Check for leaks

NOTE: The residual pressure check does not include the cold start valve. To check, reattach fuel line, energize fuel pump, and check valve visually for leaks.