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Discussion Starter · #1 ·
Hi everyone,

I had the original fuel pump replaced a few years ago because I ran into fuel trim issues. The fuel pressure was on the lower end so I decided to replace the pump with an aftermarket Bosch pump, which should be the equivalent of the original pump.

Sadly it didn't solve the problem (I still have 3,8 bar instead of 4 and 3,2 - 3,4 at full throttle instead of 3,6 or so) + there is a very distinct whine that easily finds its way into the cabin.
The colder it gets outside, the louder the whine becomes. In winter times it's really doing my head in that I'd rather take the other car.

After contemplating an m140i for a long time, a test-drive didn't give me the excitement and pleasure the ST provides, so I'm intending to keep my ST for (much) longer.
Therefore I really want to fix the noise issue.

I still have the original pump but 2 garages I spoke with advised against reusing it.
As expensive and absurd as it is, my only option seems to be a genuine Ford pump.
However, I read some genuine pumps are louder than others.
And I found a video in another topic showcasing an ST with what seems to be an equally loud pump as mine.
(video in opening post)

I can really use some advice here...
Should a genuine Ford pump be quiet?
What if I buy one and it turns out to be overly noisy again? Do I have the right to ask for another (quiet) one?
Additionally, could there be something else that causes the pump to be this noise? Power/electrical issue?
In summer, when it's 25 degrees, I can hear it slightly but it's not bothering me. In winter I can hear it over the stereo, for me it's unbearable.
I'm pretty sure my original pump wasn't this loud as I often drove with radio off so I guess it's just the pump then?

All help much appreciated!
 

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Tangerine Scream ST3 2013, with some stuff done.
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Genuine item should be better quality than some unknown pump, I hazard a guess, you could sound proof under the rear seat, which would help, it could be the electrical supply is breaking down, might be worth running new wires.
 

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Mk2 RS MP350
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I have a Mountune Pump in my RS and had a standard pump in my ST.
Neither makes/made a noticeable noise.
Are you certain it's the fuel pump as the steering pump is known to whine too?
 

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Graham - mk2 stage 3
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I agree with Alb. Never seen anything on here about fuel pump whining which makes me think that most people have OE fuel pumps. Might just be that one. If it is faulty you might be able to return it.
 

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Discussion Starter · #5 ·
Thanks everyone, that's really helpful.

@ sttwoton: The Bosch replacement pump had the same number as the original part so I thought I was buying the genuine pump, but much cheaper. Perhaps there is a difference or I was just unlucky.
Thanks for the wiring suggestion, I'll definitely mention it before replacing the pump.
Regarding sound proofing: I don't really know how to do it and I'm not sure it will make a big difference? I feel the noise is going in all directions, but you could be right. I'm also considering a catback for a bit more exhaust sound so not a fan of soundproofing the rear of the car.
@ Alb & Dabhand: yes, it's the fuel pump. It sounds exactly like in the video in the OP, high pitched. I was getting worried the noise is normal and I'm just too sensitive to it. My original pump didn't bother me and after installation of the Bosch pump I immediately noticed the loud whine. If there is no power/wiring issue, I'll replace the pump with a genuine one.
 

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Of all the cars I've owned, my ST is the only one I can remember where I actually can't hear the fuel pump prime when I turn the ignition on.

I'm not saying that your's necessarily isn't noisy, but I would be getting a firm diagnosis before being sure.

The Bosch replacement should be identical to a Ford / Volvo part but there are a lot of convincing fakes about. Did it come inside a sealed bag, inside a genuine Bosch box? If not I would be highly suspicious.
 

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Discussion Starter · #7 ·
I never noticed (didn't pay attention to it either though) a sound when turning the ignition on.
There's just a constant high pitches whine in the background that gets louder as the outside temperature drops.
It's very noticeable in the background, in the video in the opening post. Similar to my car.

I also thought it was identical, allthough I was the big price difference made me a bit wary.
The local garage bought it for me. They didn't want to install it if I bought it for them. Not enough in it for them I guess.
I worked with them before and I have nothing but good experiences. I saw the pump after they bought it but can't remember how it was packaged.
 

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Discussion Starter · #8 ·
Still unsure at this point whether I just have a noisy pump or something external is causing the pump to become noisier in certain situations.

Does anyone know why this aftermarket pump is pretty quiet when the car was parked up in the sun on a warm day, and annoyingly noisy when it's cold outside (<10°)?
Could for example the flow of petrol be reduced because of cold weather? A tube that has a sharp bend, that loosens when it's warmer? Stupid suggestion perhaps but there must be a reason why this is a winter / cold weather issue?

For the time being the local garage gave me some sound proofing material, which I will try out on a cold morning, probably next week.

If the problem is the pump indeed, he suggested a genuine Ford pump, which is fine by me. He told me however if the pump is noisy again (perhaps Ford is using other bits inside the pump compared to the earlier (quiet) models), I won't have the right to have it replaced. So if it has this high pitch whine again, that's 850 euro wasted basically.

I guess a new Ford pump will be fine, I'm just worried something else is going on. So if someone has an explanation for the noise difference between cold and warm weather, please let me know. Thanks.
 
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