Whining, whirring sound coming from the rear of my 35i??

[Roadstergal]

Any idea what this could be? It is a constant whirring sound definetely coming from the rear. I don't have any long cranking issues.

[teagueAMX]

Does it sound like it's right behind the seat area?

Your 35i has two fuel pumps. One is on the engine (it's the notorious one connected with frequent failures and long cranking) and a rear, in-tank fuel pump.

The rear one has been reported by a few people as being noisy and required replacement. Strangely enough, one person reported that the sound is louder when the tank is full, which is counter intuitive, but oh well.

How loud is the sound?


The only other thing back there that could possibly make a noise like that is the rear differential, but it's not likely making the noise.

[m6pwr]

I have the same sound in my new 35i - - very noticeable at idle and low throttle.

[Roadstergal]

Originally Posted by m6pwr

I have the same sound in my new 35i - - very noticeable at idle and low throttle.

Yes, it does sound like it is coming from behind the seat. It is also very noticeable at idle and low speeds. I don't like it. Should I bring it in?

[teagueAMX]

Originally Posted by Roadstergal

Yes, it does sound like it is coming from behind the seat. It is also very noticeable at idle and low speeds. I don't like it. Should I bring it in?

Yes

That's the rear in-tank fuel pump and they may need to replace it.

It could last a while like that, but you just don't know when it may go out.

[zEdP]

Hi,

Fuel pumps can make a high pitch sound. But if the sound changes to a low pitch humming sound, that can heard even in the car when the fuel tank is 1/4 filled, I could start to break down.

Here is what happened with my E89 low pressure fuel pump.
http://e89.zpost.com/forums/showthread.php?t=304089

EdP

[Roadstergal]

My humming sound occurs even when the tank is 1/4 full. I first noticed it about three weeks ago. Are you telling me that to replace the fuel pump that is in the gas tank, they have to remove suspension parts and take the gas tank off?

If you recall, this fuel tank problem was the main reason why I originally was going to order a 30i. I changed my mind at the last minute during the ordering process because of trim appointments that I wanted and could not get with the 30i. I was hoping that BMW corrected this before they built my car as it had been an ongoing problem. Guess not.

I am not going to be happy about them taking my car apart, that is for sure. I can't believe BMW continued to put faulty fuel pumps in their cars.

[teagueAMX]

Originally Posted by Roadstergal

My humming sound occurs even when the tank is 1/4 full. I first noticed it about three weeks ago. Are you telling me that to replace the fuel pump that is in the gas tank, they have to remove suspension parts and take the gas tank off?

If you recall, this fuel tank problem was the main reason why I originally was going to order a 30i. I changed my mind at the last minute during the ordering process because of trim appointments that I wanted and could not get with the 30i. I was hoping that BMW corrected this before they built my car as it had been an ongoing problem. Guess not.

I am not going to be happy about them taking my car apart, that is for sure. I can't believe BMW continued to put faulty fuel pumps in their cars.

Hi Roadstergal,

I know it’s very frustrating for you and I’m sorry they are putting you through this. There are actually two different issues at work here.

I went back and re-read that other thread to refresh my memory. It started off concerning the low pressure fuel pump in the tank, but changed to the HPFP issue, and went back and forth from there. As you are aware the HPFP is a major BMW screw up and they need to get that fixed ASAP. Your case is a little different. You’re suffering for a possible failure of the rear in-tank fuel pump. Those failures are happening far less frequently than the HPFP, and really all makes and models could be subject to that type of failure. All Z4’s have it as well, so even if you have bought a 30i this type of failure could happen anyway.

All fuel pumps make a bit of a hum or whirring sound, and yours is acting differently than the other ones that failed – yours makes the sound when your tank gets low, which is somewhat expected. I’m not sure how loud it get’s for you. What I suggest you do is for the next few hundred miles make a practice of filling the tank more frequently. If it gets louder than it definitely needs to be replaced.








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[m6pwr]

I'm going to stop reading this forum and learning about all the stuff wrong with my beautiful new car!

Seriously, has any one actually had their (in-tank) fuel pump fail before it was replaced? Or, will the dealer replace it when they hear it droning away in back?

[juhap]

Originally Posted by flpnout

Sometimes I hear a humming sound once I have finished driving and turned off the car completely.

Me too. But then I realize it's me who is humming happily after another great drive

[zEdP]

Originally Posted by m6pwr

Seriously, has any one actually had their (in-tank) fuel pump fail before it was replaced? Or, will the dealer replace it when they hear it droning away in back?

Yes, my 30i had a loud humming noise. I could even hear it when driving. The car runned perfectly, but the sound was simply too loud. So BMW replaced it.

Roadstergal: No suspension parts need to be removed, only the strut bars.

EdP

[mrboon]

I got the same problem, have had it for a while (8000km+). Havent been to BMW yet as the car is working fine, but the sound simply isnt nice.
Will have it looked at during the first service.

[Roadstergal]

I was already to call my dealer tomorrow to make an appointment. I will, however fill the tank up to see if I can still hear the noise. Yesterday the tank was 1/4 full when I found the noise to be almost unbearable.

[teagueAMX]

That was a question I had: how loud is it? That's way to loud. Definitely needs replacing.

Good luck

[m999psw]

Hi,
About 4 months ago I had the same annoying noise and BMW changed the fuel pump in the tank. Last week the car was at the dealers and they ran the tank down to 4 miles left and the noise started again even after putting petrol in. The car has gone back in today and they have showed me a BMW problem sheet which says that there will be - within the next couple of weeks - a new software fix for the ECU to stop the pump making a noise at idle.
So they havn't changed it and I await the update.

Paul

[GeneticX]

interesting... I have the same problem since today i think!

Also from the left begind and noticeable at idle...