Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Fuel Pump Pressure, Checking
Special Tools And Workshop Equipment Required
- Multimeter.
- fuel line adapter setV.A.G. 1318/17A. These tools may be substituted with an equivalent aftermarket tool and are also available for rental or purchase through Volkswagen.
- In line Fuel pressure gauge with shutoff. (high pressure).
Test Conditions
- Battery voltage 12.5 V
- Function and voltage supply for the Fuel Pump is OK.
- Fuel tank at least 1 /4 filled.
- Ignition switched OFF.
Test Procedure
-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK
Fuel system is under pressure! Before opening the system, place rags around the connection area. Then release the pressure by carefully loosening the connection.
Start Diagnosis
-- Disconnect fuel supply line and catch any fuel coming out with a shop towel.
Pull circlip upward to unlock fuel line
-- Install a fuel pressure gauge with appropriate adapters.
-- Open shut off valve on fuel gauge.
-- Switch ignition on and off repeatedly until fuel pressure stops increasing pressure.
-- Read fuel pressure on the gauge.
- Specified value: 3.5 to 4.3 bar
- Turn the ignition switch OFF.
If Specification Is Exceeded:
-- Check return line between fuel filter and fuel pump for kinks or blockage.
If No Malfunction In Fuel Return Line Is Found:
-- Pressure relief valve in fuel filter is malfunctioning.
-- Replace the fuel filter.
If Specified Value Was Not Obtained:
-- Check fuel pressure at the fuel filter between fuel pump and fuel filter using appropriate adapters
-- Open shut off valve on gauge and start the engine. Allow to idle.
-- Slowly close the pressure gauge shut off and note the fuel pressure.
- Pressure must increase to 4 bar.
When 4 bar is reached: Open shut off tap immediately!
Turn the ignition switch OFF.
If Pressure Has Increased During Test:
-- Fuel pump is OK. Pressure relief valve in fuel filter is malfunctioning.
-- Replace the fuel filter.
If pressure did not increase:
-- Fuel pump is faulty
-- Replace the fuel pump.
Final procedures
After the repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
- If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
- If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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