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Stan, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3526
Experience:  Technical support engineer
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I have aproblem with my fuel tank and on two occasions car

Customer Question

I have aproblem with my fuel tank and on two occasions car stalled though it was quarter tank full.The mobile mechanic I called is also puzzled because he has attempted to repair it and failed.He says that there are two compartments in the petrol tank one on the driver side and one on the passenger side.
The fuel pump is located on the driver side and that is the tank from which petrol is first consumed from and then when it is exhausted petrol should flow from the passenger side compartment to the driver side via the fuel sender.
On two occasions he found the driver side tank is empty and the other side the petrol is full hence the pump runs dry as the petrol does not move from the passenger side compartment to the driver side compartment which it should.
He then replaced the fuel sender but problem is still not sorted hence when the petrol level in the gauge drops to about a quarter the car cuts off suddenly though fuel gauge indicates there is petrol but no petrol is fed to the engine.He also checked the pump and found it to be fine of course it will not run without fuel!
On the last occasion he fed petrol manually from the passenger side to the driver side and then the car started .
hence he warned me not to let the petrol go below halfway mark and carry 5 litre in a plastic Jerry can in case of emergency.
This is all I can add.I am not an expert in cars you are but is there some sort of valve which regulates this flow?or is it something with the fuel filter?
Submitted: 3 years ago.
Category: Mercedes
Expert:  Shantal-Mod replied 3 years ago.
I'm Shantal and I'm a moderator for this topic.
I've been working hard to find a Professional to assist you with your question, but sometimes finding the right Professional can take a little longer than expected.
I was checking to see if you had already found your answer or if you still need assistance from one of the Professionals.
Please let me know if you wish to continue waiting or if you would like for us to close your question?
Thank you,
Customer: replied 3 years ago.

no require help

Expert:  Stan replied 3 years ago.
Such problem can occur due to low efficiency of the fuel pump. Although the pump still runs, the return flow is too weak to make the fuel ciculate between the two parts of the tank. This causes all of the left fuel be in the part where the return line is connected, without going to the pump' half of the tank.

Pump replacement will make the return flow strong enough for the fuel to flow to both sides of the tank.

Best regards,