Failing fuel pump? With video evidence

[jayware33]

Hi everyone,

Video Link to YouTube at bottom.

A while back I was getting a clicking from my fuel pump and asked to supply a video, well, I've managed to get it sorted.

3 mechanices say its the pump inside the tank (non-turbo model) but don't know why it's making the noise. They say its my fuel pump making the sound but baffled that I have no performance issues with the car and it's not jumping or cutting out. No high pitched whinning sound either. The noise is constant and speeds up when I apply the accelerator and is louder when there the fuel tank is near empty. dont want to spend £1,200 replacing it when the noiuse could be normal operation? In this model, you can't get to the fuel pump easily hence the high cost in labour (BMW quote).

The start of the video is me showing what it looks like at idle revs, fine and then i move the camera behind the driver seat (above the fuel tank to make the noise more apparent). It's driving me mad and no one seems to know what it is.

Any help would be great - thanks.

https://youtu.be/7u9WOgemxmI

[R.E92]

That does sound like the low pressure fuel pump.

If you have a warranty you could demonstrate the noise to a tech. Make sure you let the tank run to 1/4 to make it extra audible.
If you don't have a warranty then get a quote from an independent specialist. Should be half what BMW are charging.

You can usually diagnose fuel pump problems by checking the fuel sensors over the canbus but unlike most other BMW models the E89 doesn't have a low pressure fuel sensor that would be used to diagnose the lift pump.

[jayware33]

Just typical my car has the non accessible version .
Just moved into a new house and the thought of splashing out for a costly repair makes me sad! Needs two new rear RFT's too and a service! Ouch.

Until I get performance issues or jumping, I ain't fixing it. Drive it till it breaks, kind of ... You agree with that? Wait until there is more than just a noise?

Thanks.

[Mr_Magoo]

I have exactly the same noise coming from mine, car was in for a service today at my local independent and I asked him to check the pump due to the noise.

He told me it was working fine but seems to be a trait of the z4 to have noisy pumps. Recommended I leave it and just run the car. Has anyone actually had one fail or do they just get noisy?

Guess I'll try to run it with more than a quarter tank from now on.

P.s. He did also say that as it's a 2 seater you would notice this more readily than a 4 seater as your practically sitting next to the tank.

Thoughts anyone?

[R.E92]

He's right about hearing it more in the 2 seater. You are sat right next to it in the Z4 whereas in the 3 series the pump is under the rear seats with plenty of sound insulation from the cabin.

I had both my fuel pumps replaced last year (you don't have to worry about the high pressure fuel pump because the N52 engine doesn't have one). The low pressure fuel pump didn't make any unusual noises, I just had some less than enthusiastic starts.

The low pressure fuel pump on our cars is actually much stronger than other BMW models. You can run high ethanol mixtures without the need to upgrade it.

I don't know how the low pressure fuel pump usually fails. I haven't heard of people being stranded by a failed pump so it may just deteriorate rather than completely stop working.

The cost of a new fuel pump should be around £300 for parts. I'm not sure how easy it is to change but there's a chap over on bimmerpost with a highly modded Z4 who has recently tested several aftermarket fuel pumps in his quest for huge power. He will be able to tell you if it's possible to replace yourself and the costs involved.
Thread is here

His username is Lambobimmer, just send him a PM.

[35isDreamer]

Any help would be great - thanks.

I had very similar symptoms. Dealer replaced the fuel pump under warrantee - no quibbles at all.
They said it was cosmetic - the noise isn't an issue other than a nuisance. So it was replaced for the noise pollution aspect, not reliability.