Fuel Pressure Regulator And Residual Pressure, Checking

Function

The fuel pressure regulator regulates the fuel pressure to constant 4.0 bar.

Fig 1: Identifying Special Tools -- Fuel Pressure Regulator And Residual Pressure, Checking

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Special tools and workshop equipment required

Pressure gauge VAG1318
Adapter VAG1318/7
Adapter VAG1318/10
Hose adapter VAG1318/13

Without illustration:

Assembly tool for spring-type clamps VAS5024A

Test requirements

Parking brake must be engaged or else daylight driving lights will be switched on.
For vehicles with automatic transmission, selector lever must be in P position.
Delivery quantity of Fuel Pumps (FP) OK, checking FUEL PUMP, CHECKING , Fuel Pumps (FP), checking.

Test sequence

-- Remove fuses -13- and -14- for activation of Fuel Pump (FP) Relay -J17- and Fuel Pump (FP) 2 Relay -J49- from fuse holder.

Fig 2: Identifying Fuses

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Fuses -13- and -14- are located in fuse holder of E-box, in plenum chamber, left.

Reduce fuel pressure as follows:

WARNING:

The fuel or fuel lines in fuel system can become very hot (danger of scalding)!
In addition, the fuel system is under pressure! Before opening the system, place rags around the connection area and release pressure by carefully loosening the connection!
Wear protective goggles and protective gloves when working on the fuel system!

-- Place a rag around separating point to catch escaping fuel.

Fig 3: Identifying Fuel Supply Line

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-- Remove fuel supply line (arrow).

When the fuel pressure is reduced:

-- Tighten threaded connection again.

-- Loosen spring clip and remove fuel supply line from connecting piece at fuel rail.

-- Connect pressure gauge to supply line VAG1318 and fuel rail using adapters VAG1318/7, VAG1318/10, and VAG1318/13.

Fig 4: Connecting VAG1318 Pressure Gauge To Supply Line And Fuel Rail Using V.A.G 1318/7, V.A.G 1318/10, And V.A.G 1318/13 Adapters

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-- Secure hose ends using clamps -2-.

NOTE:

It is important that fuel hose ends are secured with clamps!

-- Open shut-off valve of pressure gauge. The lever -1- points in the direction of flow.

-- Insert fuses -13- and -14- in the fuse holder.

Fig 5: Identifying Fuses

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-- Start engine and let run at idle.

-- Measure fuel pressure.

Specified value: approx. 4.0 bar positive pressure

-- Switch ignition off.

If specified value is not obtained:

-- Check delivery quantity of Fuel Pumps (FP) FUEL PUMP, CHECKING , Fuel Pumps (FP), checking.

-- Replace fuel pressure regulator if necessary.

-- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.

-- Generate readiness code.

If specified value is obtained:

-- Now check for proper seal and residual pressure. Observe pressure drop on pressure gauge for this. After 10 minutes

at least 3.0 bar positive pressure should still be present.

If residual pressure falls below 3 bar positive pressure:

-- Check pressure gauge for proper seal.

-- Check check valves of Fuel Pumps (FP) FUEL PUMP, CHECKING , Fuel Pumps (FP), checking.

When removing pressure gauge after completed test:

-- Remove fuses -13- and -14- for activation of Fuel Pump (FP) Relay -J17- and Fuel Pump (FP) 2 Relay -J49- from fuse holder.

Fig 6: Identifying Fuses

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-- Place a rag around separating point to catch escaping fuel.

Fig 7: Identifying Fuel Supply Line

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-- Remove fuel supply line (arrow).

When the fuel pressure is reduced:

-- Tighten threaded connection again.

-- Remove pressure gauge with adapters.

-- Connect fuel supply line to connecting piece of fuel rail and secure it using spring clip.

-- Insert fuses -13- and -14- in the fuse holder.

Fig 8: Identifying Fuses

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.

-- Generate readiness code.