Polo 9n Fuel Pump

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chucky87
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Car Make: VW
Car Model: Polo Vivo GT 3-dr

Polo 9n Fuel Pump

Post by chucky87 »

Hello good people

I am seeking some technical advice for the above, this is my mom's car. I am in the IT industry so understand the technical basics of mechanics and electronics, my grandfather taught me a lot about cars back in the day. I am confident with the basics, so consumable/filter replacements, basic troubleshooting with fuses, relays, globes etc etc.

Car in question is a 2005 VW Polo 1.6 Comfortline hatch, with 171000kms on the clock. It has a FSH, and has been in daily use for most of it's life. It is stock, however the cat died so henceforth pipe was replaced with a Cowley Free-flow which sounds pretty good, for entry-level. This was the most cost effective repair instead of getting a new cat at around R7000.

Problem is this; on cold start car usually runs fine to your destination. When doing a warm start after about half an hour, the engine will not idle smoothly and there is no power whatsoever, with a strong petrol smell coming through the air vents. This seems to me that the ECU is triggering limp mode due to over-fueling or low pressure from the fuel pump. Backfires occur easily when throttle depressed further in attempts for more power, as excess fuel isn't being combusted and is therefore naturally heavy on gas in this mode.

We have taken it into a German car service centre in Pinetown, KZN, for scans. They found the O2 sensor and coolant temp sensor reporting error codes on their diag tool, however suggested we get an auto electrician to run some tests too, as it seemed to be more of an electronic/electrical problem than mechanical. They referred us to another specialist, who ran numerous diagnostics twice or thrice, and could not find anything wrong with the sensors, wires, ECU or electrical side of things. We suggested my theory above, and so they took it to a fuel pump specialist to confirm.

They said that the pump itself is causing the issue with low pressure, and would have to be replaced. These are not cheap, so I am wanting to find out if anyone has any experience with VW economy or reconditioned parts from the dealers, or a Goldwagen OEM alternative? Also, how difficult would it be for a self-install, once the part has been sourced? The back seat needs to be lifted or removed, in order to access the pump. I have not had a look at service manuals or YouTube just yet, but am hoping it is something we can do ourselves.

Has anyone had any experience with this? If so, is it a relatively easy swop out? The car has recently had a service at 170000kms, so oil change, replacement of oil, air, fuel, and pollen filters. Just before that was done, I replaced all 4 sparks and HT leads as cylinder 3 spark was arcing outside the engine, causing misfiring and also no power. Engine is mechanically sound and she goes like a bomb in normal mode.

Some advice would be greatly appreciated, I do apologize for the long post, but had to include all the details and history of the vehicle.

Thanking you in advance.
“The sad thing about true stupidity is that you can do absolutely nothing about it.” - John Cleese

Current ride:

2013 VW Polo Vivo GT
Decat & stainless muffler tip, otherwise stock
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panic-mechanic
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Re: Polo 9n Fuel Pump

Post by panic-mechanic »

So did you change the water temp sensor?.
Stephan van Tonder - Jhb - Putfontein Benoni
'05 Audi A6 3.0L TDI Avant
'09 Touareg 3l TDI
'13 VW CC 2l tdi (repair project)
'05 Touareg v10

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chucky87
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Car Make: VW
Car Model: Polo Vivo GT 3-dr

Re: Polo 9n Fuel Pump

Post by chucky87 »

No, not as yet bud. The auto sparky's said all sensors checked out fine on their tests that were run.
“The sad thing about true stupidity is that you can do absolutely nothing about it.” - John Cleese

Current ride:

2013 VW Polo Vivo GT
Decat & stainless muffler tip, otherwise stock
User avatar
panic-mechanic
Panic's Place
Posts: 26715
Registered for: 21 years 7 months
Membership No: 79
Location: Benoni, putfontein.

Re: Polo 9n Fuel Pump

Post by panic-mechanic »

the water temp sensor reporting failed by the one company will do all the stuff you describe. Change that first before anything else.
Stephan van Tonder - Jhb - Putfontein Benoni
'05 Audi A6 3.0L TDI Avant
'09 Touareg 3l TDI
'13 VW CC 2l tdi (repair project)
'05 Touareg v10

Perfect Power dealer. I do dyno tuning.
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chucky87
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Posts: 5
Registered for: 5 years 5 months
Car Make: VW
Car Model: Polo Vivo GT 3-dr

Re: Polo 9n Fuel Pump

Post by chucky87 »

This is what I've seen and heard. Wanted to get an expert opinion before replacing parts, so thanks for your response panic, will get this replaced first and see how it goes. Will update in due course.
“The sad thing about true stupidity is that you can do absolutely nothing about it.” - John Cleese

Current ride:

2013 VW Polo Vivo GT
Decat & stainless muffler tip, otherwise stock
User avatar
chucky87
Enlisted
Posts: 5
Registered for: 5 years 5 months
Car Make: VW
Car Model: Polo Vivo GT 3-dr

Re: Polo 9n Fuel Pump

Post by chucky87 »

Sorry for the delayed response panic, been very busy this time of the year! So managed to replace the sensor, and all seems to be well. My mom has been driving around and warm starts between destinations have been fine. Looks like all is back to normal, fuel economy is fine and no more limp modes. Stoked on the outcome, your advice and assistance has been greatly appreciated! Best wishes for the festive season :)
“The sad thing about true stupidity is that you can do absolutely nothing about it.” - John Cleese

Current ride:

2013 VW Polo Vivo GT
Decat & stainless muffler tip, otherwise stock
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