Fuel Pressure And Residual Pressure Before High Pressure Pump, Checking

WARNING: This page is about a different variant/trim than selected.

Special tools and workshop equipment required

Pressure gauge K-Jetronic V.A.G 1318
Adapter V.A.G 1318/11
Adapter V.A.G 1318/17-1 from adapter kit V.A.G 1318/17
Double connection V.A.G 1318/23
Remote control V.A.G 1348/3 A with adapter cable V.A.G 1348/3-3
Connector test kit V.A.G 1594 C or V.A.G 1594 A
Measuring container, fuel-resistant

Test Conditions

Battery voltage at least 12.5 Volts.
Fuel filter OK.
Fuel tank at least ¹ /₄ full.
Fuel Pump (FP) Control Module -J538- OK; checking
Ignition switched off.

Test Sequence

-- Remove rear seat bench. Refer to Removal and Installation .

-- Unclip retainers -arrows- of the cover for sealing flange.

Fig 1: Identifying Cover From Fuel Delivery Unit

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-- Disconnect electrical harness connector -arrow- at locking flange.

Fig 2: Identifying Fuel Delivery Unit Connector

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-- Connect remote control V.A.G 1348/3 A with connection V.A.G 1348/3-3 to contact -1- using an adapter cable from the connector test set V.A.G 1594 C.

Fig 3: Identifying Jumper Cable From Electrical Test Lead Set Connected To Fuel Delivery Unit Terminal And Vehicle Ground

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-- Using insulating tape, tape over the second contact of connection V.A.G 1348/3-3 to prevent a short circuit -arrow-.

-- Connect contact -5- to vehicle Ground (GND) using a jumper cable from the connector test set V.A.G 1594 C.

-- Connect alligator clip to vehicle battery (+).

-- Remove fuel filler cap from fuel filler tube.

WARNING:

The fuel system is pressurized (low pressure). Wear protective eyewear and clothing in order to avoid injuries and contact with skin. Before opening the fuel system, place a rag around the connection. Then reduce residual pressure by carefully removing connection.

-- Disconnect fuel supply line -arrow-.

Fig 4: Attach Fuel Line Feed Adapter V.A.G 1318/23

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-- Attach Fuel Line Feed Adapter V.A.G 1318/23 and Adapter V.A.G 1318/17-1 to Fuel Inj. Pressure Gauge-CIS V.A.G 1318.

Fig 5: Identifying Attachment Of Fuel Pressure Test Set (High Pressure)

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-- Push adapter V.A.G 1318/17-1 onto the disconnected fuel supply line.

-- Attach Adapter V.A.G 1318/11 to Fuel Inj. Pressure Gauge-CIS V.A.G 1318.

-- Push an assisting hose -arrow- onto it and hold it into a measuring container.

-- Open shut-off valve on Fuel Inj. Pressure Gauge-CIS V.A.G 1318. The lever points in the direction of flow.

-- Bleed fuel system by pressing remote control briefly.

-- Close shut-off valve on Fuel Inj. Pressure Gauge-CIS V.A.G 1318. Lever stands perpendicular to direction of flow -arrow-.

Fig 6: Closing Pressure Gauge Cut-Off Valve

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-- Press remote control switch until pressure increase is no longer observed on Fuel Inj. Pressure Gauge-CIS V.A.G 1318.

Specified value: Approximately 6 bar (4 to 8 bar) positive pressure

If specification is not obtained:

-- Check delivery rate of fuel pump. Refer to Diagnosis and Testing .

Residual Pressure, Checking

-- Check for leaks and residual pressure by observing pressure drop on Fuel Inj. Pressure Gauge-CIS K-Jetronic V.A.G 1318.

After 10 minutes there must be a residual pressure of at least 3 bar.

If residual pressure drops below 3 bar:

Check connection between Fuel Inj. Pressure Gauge-CIS K-Jetronic V.A.G 1318 and fuel supply line for leaks.
Check Fuel Inj. Pressure Gauge-CIS V.A.G 1318 for leaks.
Check fuel lines and their connections for leaks.
Replace fuel filter with integrated fuel pressure regulator. Refer to Removal and Installation . Then repeat test.
If fuel filter is OK, replace fuel pump. Refer to Removal and Installation .

Assembly is in reverse order of removal, note the following:

-- Ignition must be switched off.

Fig 7: Identifying Attachment Of Fuel Pressure Test Set (High Pressure)

Courtesy of AUDI OF AMERICA, LLC

NOTE:

Before disconnecting pressure gauge, release pressure by opening shut-off valve. Hold assisting hose in a container when doing so.

-- Reconnect fuel supply line (pay attention to cleanliness and leaks).