noise in fuel tank on my 95 bmw 740i E38

there was a humming noise come from the back seat area... so suspected the fuel pump and put in a nea one... But the noise did not go away. I then changed the fuel sending unit on the left side
because the noise seemed to be coming from there. But the noise did not go away... Before doing anything else I want to know what else should I check... or what else could it be that is causing that noise
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snipped-for-privacy@gmail.com wrote:

Rear wheel bearing?
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it makes the noise while standing still and the transmission in park. I dont think it the bearing.
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Does it make the sound with the gas cap off? You can sometimes get funny noises from the tank venting system.
If it is the fuel pump, it will usually be much louder when the tank is low than when the tank is full.
Some fuel pumps are just noisy. Life is like that. --scott
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Diff - is the noise worse in reverse or sharp corners? This can often be ignored - I had one whirr in reverse for 11 years until I sold the car.
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wrote:

the noise it just there all the time. 10 seconds after starting the car the noise starts up.... It is coming from the gas tank area. And is muffled a little when the sound deadening pad is replace onto the fuel pump access cover plate. but its there even in park
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Fuel pump then - look for a leak and bleed the line.
Is there any sort of a pressure switch which should switch it off once satisfactory pressure is achieved?
PS my third 735i used to whirr for a few seconds after switch on while it pressurised the fuel line - it was best to wait for this to end before trying to start the engine.
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It's the fuel pump.
Just because you can hear the pump does not mean anything.

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I replaced the old fuel pump with a new one already and the new is still there. The pump that is in there now is only 3 days old
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If the noise starts when you turn the key on, it's the pump. If the noise does not start until you are driving, then it could be the diff.
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CD player back there gone bad?
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