Fuel Pressure, Checking

WARNING: This page is about a different car, the 2010 Volkswagen Jetta, 2009 Volkswagen Jetta, 2009 Volkswagen GLI, 2008 Volkswagen Jetta, and 2008 Volkswagen GLI. However, it is still accessible from the selected car via links, so may be relevant.

The fuel pump function must be checked. Refer to FUNCTION AND VOLTAGE SUPPLY, CHECKING .

NOTE:

Output diagnostic test mode activates the fuel pump.

WARNING:

The fuel system is under pressure!

Always wear protective eyewear and protective clothing to prevent injuries and fuel from coming in contact with your skin.
Before loosening line connections, place a cloth around the connection point. Then release pressure by carefully pulling off the line.

-- Disconnect the fuel supply line -2-. Push the locking ring upward and into the housing.

Fig 1: Disconnecting Ventilation Line

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-- Connect the pressure tester VAS 6550 to the hoses VAS 6550/1 and VAS 6550/2 and to the fuel supply lines.

Fig 2: Connecting Pressure Tester VAS 6550 To Fuel Supply Line Using Adapters VAS 6550/1 And VAS 6550/2

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-- Make sure the drain is closed and the shut off levers are open.

-- Activate the fuel pump with output diagnostic test mode to build fuel pressure.

-- Check the fuel pressure on the pressure tester.

Specified value: 4.0 to 7.0 bar

If the fuel pressure is OK, check the residual pressure. Refer to RESIDUAL PRESSURE, CHECKING .

If the Specification is Exceeded:

-- Check the return line between the fuel filter and the fuel pump for kinks or blockages.

If no malfunction can be found:

-- Replace the fuel filter, the pressure relief valve inside the fuel filter is faulty.

If the Specification is not Obtained:

-- Check the fuel pressure before the fuel filter as follows:

-- Disconnect the fuel supply line -arrow- from the fuel filter.

Fig 3: Fuel Supply Line At Fuel Filter

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-- Using the hoses VAS 6550/1 and VAS 6550/2, connect the pressure tester VAS 6550 between the fuel filter and fuel supply line.

Fig 4: Connecting Pressure Tester VAS 6550 Between Fuel Filter And Fuel Supply Line Using Hoses VAS 6550/1 And VAS 6550/2

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-- Make sure the drain is closed and the shut off levers are open.

Fig 5: Identifying Drain Valve -C- Is Closed And Shut Off Valves -A And B- Are Open

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-- Turn on the ignition and actuate the fuel pump using the output diagnostic test mode.

-- Close the shut off lever -A- while the fuel pump is running.

Pressure must increase to a min. 7.0 bar.

-- If 7.0 bar is reached, open the shut off lever again immediately!

If the pressure has increased:

-- Replace the fuel filter, the fuel pump is OK but the pressure relief valve in the fuel filter is faulty.

If the pressure does not increase:

-- The fuel pump is faulty, replace the fuel delivery unit. Refer to FUEL DELIVERY UNIT .