System Pressure Test

CAUTION: When working on fuel system, always follow these precautions on cleanliness
- thoroughly clean all unions and area near connections before disconnecting
- place removed parts on a clean surface and cover over. Use paper or plastic sheet. Use only lint-tree cloths
- components which have been opened or disassembled must be covered or sealed carefully if repair cannot be carried out immediately
- only install clean components
- only unpack replacement parts immediately before they are installed
- do not use parts that have been stored loose (for instance, in toolboxes)
- when fuel system is open, do not work with compressed air if this can be avoided or move car unless absolutely necessary

SYSTEM PRESSURE, CHECKING

WARNING: Fire hazard. Do not smoke or have anything in area than can ignite fuel.





- using new sealing washers and line adapter VW 1318/5 (1), connect pressure gauge VW 1318 between fuel line at cold start valve 2 and lower chamber test connection of fuel distributor 1.
^ gauge lever positions: A open
B closed

- switch OFF US 4480/3
- remove fuel pump relay and jump socket with US 4480/3
- remove electrical connector from differential pressure regulator
- open valve on VW 1318 pressure gauge
- turn ON US 4480/3
- system pressure must be 5.2 to 5.6 bar (75 to 82 psi)

If pressure BELOW specs:
- check fuel pump delivery quantity

If fuel pump delivery quantity OK
- replace diaphragm pressure regulator

If pressure ABOVE specs
- disconnect fuel tank return line from diaphragm pressure regulator and repeat test
- system pressure must be 5.2 to 5.6 bar (75 to 82 psi)

If pressure OK
- check for plugged fuel return line

If pressure NOT OK
- replace diaphragm pressure regulator

NOTE: System pressure not adjustable