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Polo Strange Noise Near Fuel Tank

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matthew.bicknell
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Drives: Polo 6C 2015 SEL 1.2 110
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Polo Strange Noise Near Fuel Tank

Post by matthew.bicknell » Wed Jun 13, 2018 11:40 pm

Hi all,

Wondering if anyone could shed some light on what the strange ticking/vibrating noise is that is coming from near the fuel tank under my car. The noise started about 3 weeks ago from memory.

The noise can be heard inside the back end of the car especially around the rear footwells/tunnel.

I have attached a link to my onedrive folder containing 2 videos: 1 of the underside of the car and another of the inside of the car demonstrating the sound. There is also a photo of the idling RPM too.

https://1drv.ms/f/s!AkMrqw9ifexFnDNgHv7snELkfvlJ

The noise seems to be coming from the cylindrical silver thing under the car that is shown in the video but I am not 100% sure what this is.

The car is just out of warranty by 2 months so hoping someone could give me some suggestions.

Thanks,

Matt

RUM4MO
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Re: Polo Strange Noise Near Fuel Tank

Post by RUM4MO » Thu Jun 14, 2018 6:29 pm

That silver cylinder is the fuel filter/pressure regulator assembly. I’d expect any noises to come from either that or the low pressure fuel pump which should be down there - thoughI’ve never actually spotted it.

I’ve never been aware of any noises from that area on my wife’s August 2015 one that is same as your model.

matthew.bicknell
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Re: Polo Strange Noise Near Fuel Tank

Post by matthew.bicknell » Thu Jun 14, 2018 11:37 pm

Thanks for the info RUM4MO

Going to contact the dealer and see how I get on. Shame the car is just out of warranty though.

veteran
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Re: Polo Strange Noise Near Fuel Tank

Post by veteran » Fri Jun 15, 2018 12:17 am

On my Polo 1.2, under the rear seats, there's a large access cover and electrical connectors for what I understand to be one of two fuel pumps. Its position corresponds to the top of the fuel tank. It's noise coming from that that you can probably hear. Just lift you rear seats, pull aside the bit of carpeting there, and you'll see what I mean. It's no surprise therefore that you can hear it "inside the back end of the car, especially around the rear footwells/tunnel".

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alexperkins
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Re: Polo Strange Noise Near Fuel Tank

Post by alexperkins » Fri Jun 15, 2018 1:02 pm

The TSI has a high pressure fuel system so its quite possible its the fuel pipes vibrating against the plastic housing underneath and should be fixable by adjusting their position slightly.

wolfie
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Re: Polo Strange Noise Near Fuel Tank

Post by wolfie » Fri Jun 15, 2018 3:45 pm

alexperkins wrote:
Fri Jun 15, 2018 1:02 pm
The TSI has a high pressure fuel system so its quite possible its the fuel pipes vibrating against the plastic housing underneath and should be fixable by adjusting their position slightly.
I've also posted on about this subject in another thread. Now this is all based on thinking about it, as opposed to having any real proof, but here goes. I'm of the same mind as yourself, I suspect the "tick" is simply caused by pressure pulses coming back down the fuel lines from the high pressure pump. I suspect the fuel filter has a none return valve and that the pulses may be causing it to close under certain cercumstances, thus you hear the "Tick"

The TSi fuel system is quite complex, the lift pump in the tank is controlled by a little PWM gizmo so the fuel delivered to the high pressure pump can actually vary in pressure even before the high-pressure pump does it's stuff.

If I'm 100% honest I bought my little Polo 1.2Tsi as a keeper, though I'm not sure it was best decision I've ever made as they look as if they have the potential to have quite complex problems as they age. That's not counting the known issues like cam chains. (I'd want mine done if I kept the car much longer) I actually caught myself looking at a CityGo the other weekend so I must be getting that itch to swap.

RUM4MO
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Re: Polo Strange Noise Near Fuel Tank

Post by RUM4MO » Sat Jun 16, 2018 4:55 pm

alexperkins wrote:
Fri Jun 15, 2018 1:02 pm
The TSI has a high pressure fuel system so its quite possible its the fuel pipes vibrating against the plastic housing underneath and should be fixable by adjusting their position slightly.
Alex, remember that while the TSI engines have a high pressure fuel system, the electric pump near the tank is only a normal pressure one, ie known as low pressure and it lifts the fuel up to the mechanical high pressure pump which is mounted above the cam shafts. Your points about fuel pipes moving and so maybe causing noises is spot on though. The only trouble I've had with a 2015 1.2 16V TSI 110PS is the low pressure fuel line was banging off or just touching and so chaffing the rubber and polishing the A/C discharge pipe, I sorted that with a bridging clip so that it gets held away from the A/C discharge pipe - ie like it should have been for that age of car going through the factory!

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