Fuel Pressure Regulator: Testing and Inspection
Fuel pressure regulator and residual pressure, checkingWARNING: Fire Hazard. Do not smoke or have anything in area that can ignite fuel!
The fuel pressure regulator regulates the fuel pressure in proportion to intake manifold vacuum.
- wrap a lint free cloth around pressurized fuel hose to prevent fuel overspray
- located between fuel rail and fuel pump after-run pressure switch
- disconnect hose 1 from pressure switch 2 and catch any fuel that runs out
- connect pressure tester VAG 1318 to disconnected hose 1 using adaptor VAG 1318/10
NOTE: The valve on the pressure gauge must be in the closed position, that is; the lever must be at a right angle to the direction of flow.
- start engine and let run at idle
- observe fuel pressure
- must be approx. 2.5 bar
- disconnect fuel pressure regulator vacuum hose from intake manifold (arrow)
- fuel pressure must increase to approx. 3.0 bar
- switch OFF ignition
- check for leaks and residual pressure by watching pressure drop on gauge
- after 10 minutes there must be 2 bar minimum pressure
If the residual pressure drops below 2 bar
- start engine until fuel pressure has built up
- switch OFF ignition, at the same time securely clamp fuel return hose (blue) and observe pressure drop on gauge
- if pressure does not drop; pressure regulator is defective
If pressure still drops check the following
- hose connections are leaking
- fuel rail 0-rings are leaking
- fuel injectors are leaking
- fuel pump check valve is leaking
- pressure gauge shut-off valve is leaking
- repair or replace as necessary
- drain fuel from VAG 1318 before removing the pressure gauge