# fuel pump noise...



## bmw325 (Dec 19, 2001)

Do you notice a loud "whir" noise from you car? Please state if you do, and what your build date is. My car's pump has always been loud, and i've definiltely noticed it on other 01 e46s. Earlier e46s seem quiet, and I'm not sure about later e46s. i noticed that BMW has rediesigned the pump 3 times, so I'm wodnering if it was just that 2nd redesign that was noisy. Is so, I'll just pay $50 or 60 and get the later design (if it is indeed quieter).


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## eelnoraa (Oct 13, 2003)

I have 04 330i, Jan 2004 build. I do have the feul pump noise. It doesn't sound very loud or in a bad way. It kind of sounds like aftermarket intake, the sound of sucking air. If I seat in the driver seat, open the door, I cannot really hear it. It only become obvious when I listen by the rear right wheel.

eel


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## Kaz (Dec 21, 2001)

It's not loud enough that I notice unless I'm in my garage and it's very quiet.


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## bmw330zhpfan (May 1, 2004)

*Fuel System*

I have a 04 330Ci and I've noticed general fuel system noise when the car is running and I am outside the car. 
I actually work in the auto industry (engineering) for a fuel delivery supplier, so I am very familiar with fuel system function / subjective noise evaluation. BMW does in fact have an exterior requirement for sound pressure level, but I am not certain what it is for the E46. We have been awarded and are currently in the prototype phase for the 2007 E70 (X5 renewal). That is why I am familiar with the exterior SPL requirements.

The E46 system features two pumps. The main pump is on the passenger side (fill neck side). This is where the electric fuel pump is located. It is a turbine pump and if you hear anything it would be at a very high frequency (whine). This is typically not an issue with well engineered pumps. The transfer pump (a jet / venturi pump) is located on the driver side. It's function is simply to transfer fuel from the sub side of the fuel tank to the main side of the fuel tank (keep in mind as a rear drive vehicle that the drive shaft divides the tank into two chambers). So in simple terms, all fuel supplied to the engine is delivered from the main side. 
In addition, as fuel level in the tank decreases to 1/2 and below, the sub side tank is essentially empty (fuel may slosh over during aggresive driving, but is quickly transferred back once stable conditions are obtained), however, the jet pump is continually powered. I have noticed in fuel levels of 1/2 and below that I can hear the jet pump (a fluid rushing noise) from outside the vehicle as surronding fluid no longer is around the jet pump helping to silence it. 
I suggest you avoid replacing the fuel delivery system with an older unit. Fuels are ever changing and materials / components are continually being upgraded. In addition, current draw, hot fuel performance and low voltage flow are all elements of systems specific to vehicle requirements. If anything, change only the pump (if possible and flow rates are not compromised) leaving the fuel delivery module (or sender unit) unchanged. 
We provide fuel systems for OEMs worldwide. The system in the E46 is world class. :thumbup: 
General noise is typical and essentially indicates everything is working!


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## bmw325 (Dec 19, 2001)

bmw330zhpfan said:


> I have a 04 330Ci and I've noticed general fuel system noise when the car is running and I am outside the car.
> I actually work in the auto industry (engineering) for a fuel delivery supplier, so I am very familiar with fuel system function / subjective noise evaluation. BMW does in fact have an exterior requirement for sound pressure level, but I am not certain what it is for the E46. We have been awarded and are currently in the prototype phase for the 2007 E70 (X5 renewal). That is why I am familiar with the exterior SPL requirements.
> 
> The E46 system features two pumps. The main pump is on the passenger side (fill neck side). This is where the electric fuel pump is located. It is a turbine pump and if you hear anything it would be at a very high frequency (whine). This is typically not an issue with well engineered pumps. The transfer pump (a jet / venturi pump) is located on the driver side. It's function is simply to transfer fuel from the sub side of the fuel tank to the main side of the fuel tank (keep in mind as a rear drive vehicle that the drive shaft divides the tank into two chambers). So in simple terms, all fuel supplied to the engine is delivered from the main side.
> ...


Cool. Thanks for the detailed response. The pump I'd consider using would actually be a later unit (it was redesigned again in septermber 01). The noise I hear is louder than any other car I've come across (except some other e46s). ITs a loud electrical kind of whir or hum. Its definitley not world class. Earlier cars don't seem to have the noise-- i'll have to pay attention to some more recent e46s when I see them to see if its worth changing the pump. Its a minor thing, but I don't mind addressing it for $50-$60.


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## bmw330zhpfan (May 1, 2004)

*Fuel System*

Be certain the re-designed assembly does not impact the fuel level sender A(float arm based variable output resistor). 
These things change like mad (perceived issues with accuracy, resistance value output changes, etc.) Again, with newer fuel formulations, these changes happen at an alarming rate. Many times they are not backward compatible. The SA should know this.


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## alpinewhite325i (Jan 20, 2002)

I have the same noise; although I only notice it if the car is running in the garage. It doesn't bother me. Perhaps it's a good thing. If the pump starts going bad maybe you'll get a little advanced warning by a change in the sound!!

Build: 04-01


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## slee421 (Jun 8, 2004)

Build date is may 01. i know when the car is first started, the extra whirring type noise is there, but i cant hear it once i get in the car. essentially a minor problem to me, but something i am aware of. I know my z3 has this sound too, and its good to see such a detailed response. thanks. I dont think i would replace the unit because i believe the sound goes away after driving awhile, probably the whole 2 sided gas tank thing.


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## Kaz (Dec 21, 2001)

I can think of 2 other cars that make the same noise, but VERY loudly:

any W126 Benz (80s S-class)
newer Suburbans/Tahoes


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## edsmax (Jul 28, 2003)

5/01 build date on my 330...my fuel pump is one of the loudest I have ever heard. I've just gotten used to it.


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## bmw325 (Dec 19, 2001)

Cool. Thanks for all the responses. I wonder what BMW did during 01 that made the pump so much louder.

Kaz- I guess I never noticed it on the W126, probably because most of the cars I've seen have been diesels so that kind of drowns out any other noise.


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## sargepug (Aug 12, 2004)

I'm glad a did a search and found this thread. I have noticed the same high pitched hum and suspected it was a problem w/ the fuel pump. Now I understand it is normal. It is strange though abd have never heard a fuel pump noise so prevelant as this.


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## guzplace (Apr 16, 2004)

I did not see any new designs in the ETK all the same part numbers from 1999 to 2003
as far as i am concerened

what do you think guys ?


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## nvrsummer21 (Sep 28, 2004)

Kaz said:


> It's not loud enough that I notice unless I'm in my garage and it's very quiet.


 mine is quiet igot an e30 but it sounds like water swishing around maybe iu need a new one? or it normal


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## EdCT (Mar 14, 2002)

robg said:


> Cool. Thanks for all the responses. I wonder what BMW did during 01 that made the pump so much louder.
> 
> Kaz- I guess I never noticed it on the W126, probably because most of the cars I've seen have been diesels so that kind of drowns out any other noise.


Mine's fairly loud as well.

2k 323i, August 2k build.

Ed


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## slee421 (Jun 8, 2004)

i think my build was 3/01. sometime around then, bought 5/01. anyways i got that same whirring noise, but i usually dont pay any attention to it. I just let it be. I know its normal. When im in the car, the cabin is nice and quiet so i dont mind it when i have the car on and the door open. Im just glad that i dont have any worse problems...  knock on wood....


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## sargepug (Aug 12, 2004)

nvrsummer21 said:


> mine is quiet igot an e30 but it sounds like water swishing around maybe iu need a new one? or it normal


I think the e30's are excluded from the convo. I think it is an e46 problem. I had 2 e36's (96' 318is & 99' M3) and never heard anything in them.


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## johnf (Sep 16, 2003)

sargepug said:


> I have noticed the same high pitched hum and suspected it was a problem w/ the fuel pump. Now I understand it is normal. It is strange though abd have never heard a fuel pump noise so prevelant as this.


Did you ever drive the car until the tank was close to empty? That is the time-honored way to produce a noisy BMW fuel pump.

For the survey:
aircraft-like (ca. 400 hz) whine from fuel pump on previous 2/93 318i after once running close to empty
No noise on current 6/96 318is with original pump


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## sargepug (Aug 12, 2004)

johnf said:


> Did you ever drive the car until the tank was close to empty? That is the time-honored way to produce a noisy BMW fuel pump.
> 
> For the survey:
> aircraft-like (ca. 400 hz) whine from fuel pump on previous 2/93 318i after once running close to empty
> No noise on current 6/96 318is with original pump


Nope, I try to never let it get lower than 1/4, especially during break in.


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## johnf (Sep 16, 2003)

sargepug said:


> Nope, I try to never let it get lower than 1/4, especially during break in.


A friend did on his second (or third?) E46 after which the fuel pump started to whine. He is more careful now.


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