Noise from fuel tank when 1/2 full
Topic number

LI47.10-P-079604

Version

1

Function group

47.10 - Fuel tank

Date

8/15/25

Validity

Model series 214/206 with gasoline engines

Reason for change

Complaint
Audible "slurping" operating noise from the fuel tank

Cause
Conditions:
•
•

•
•
•

The fuel tank is around half full
The secondary chamber is almost empty. The suction jet pump suctions up small quantities of fuel and air. This
results in vibrations and turbulence, which make noises. These noises may sound like slurping. The fuel pump
and the drained secondary chamber amplify certain noises which can be loud or shrill. The viscosity of the fuel
and the intensity of the fuel pump also impact the noises.
The fuel level is in the area of the saddle overflow in the primary chamber. The fuel mixed with air flows back into the secondary chamber. The noises may therefore be audible for longer
If the primary chamber is no longer in the area of the saddle overflow, the noises should disappear because the
secondary chamber no longer receives fuel.
The area of the saddle overflow in the primary chamber is around +/- 2 liters of fuel volume (fuel gauge shows
around half full).

Attachments
File

Description

Grafik Arbeitsgeräusch Saugstrahlpumpe_Graphic
working noise suction jet pump_V1.pdf

Remedy
•

Refill/drain approx. 5 liters of fuel; if the noise is reduced/is no longer present due to this, the circumstance specified above is present

Further measures may cause a reduction in noises in the specified area:

•

In isolated cases, a fuel tank installed under stress may amplify the noises. The installation position of the fuel
tank and the contact surfaces on the body-in-white should be checked here. To do so, release the fuel tank and
refasten it, see WIS.

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© Copyright Mercedes-Benz AG

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•

Replacement of component parts such as fuel tank/delivery module does not provide a remedy!

If a similar noise is heard, but the tank volume is 3/4 or 1/4 and not 1/2 as described above, another circumstance is
present

WIS-References
Document number

Title

Note

AR47.10-P-4100MRV

Remove/install fuel tank

Do not replace any component part,
refasten as required

Disclaimer
NOTE: The information contained in this document is intended for use by trained, professional technicians with the
knowledge to properly and safely perform diagnosis and repairs on Mercedes-Benz vehicles, using Mercedes-Benz
approved tools and equipment. It informs service technicians about conditions that could occur in certain vehicles and
provides information that could assist in proper vehicle diagnosis, service, or repair. It does not indicate that a defect
is present in any vehicle referenced in this document nor does it imply warranty coverage. DO NOT assume that a
symptom or condition, or a described cause of a symptom or condition, affects any particular vehicle or groups of vehicles, or that a described repair applies to any particular vehicle or groups of vehicles. There can be multiple causes
resulting in the same or similar symptoms or conditions described in this document, and trained professional service
technicians must use their diagnostic skills to make evaluations on a case-by-case basis. The information contained
in this document does not guarantee warranty coverage nor does it extend the vehicle’s warranty in any way.

Symptoms
Power generation > Fuel system > Noises > Steam bubbles hissing noise
Power generation > Fuel system > Fuel pump > Noise
Power generation > Fuel system > Fuel tank > Noises > Whistles

Operation numbers/damage codes
Op. no.

Operation text

15.08.2025 17:52
© Copyright Mercedes-Benz AG

Time

CCUSHWA

Damage
code

Note

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