Golf MK3 GTi 2L 8V fuel or power issues

Hi all,

I have a Golf MK3 GTi 2L 8V, which I imported from the UK to Australia 6 years ago.

It's been great, however always had a slight hesitation at 2000 revs. Also, if you started the car and revved high and take the foot off quick, it drops and can cut out. Then it takes a few minutes to reset,. If you try to start it to early, it just cuts out again and not idle.

A month ago, this cutout event happened. I waiting the normal kind of time for a reset, and started her up. Now she is running really rough all the time, and when you put pressure on the accelerator, the car struggles to deliver power to the engine.

We've been working on fixes at the garage.

Firstly, the engine is timing fine and running well. No pressure test issues too. All plugs are new and sparking. I've replaced the MAF. I've tested the ECU, TWICE! No issues. There are also no error codes. I've replaced a whole lot of corroded wiring. I checked the throttle body, and it's all good.

The one thing that is baffling, is that when you block the fuel return, the problem goes away. Firstly I swapped the lines in and out of the fuel rail to see if there were blockages. Same running issues continued. So then I replaced the fuel rail. The fuel pump also seems to be running fine. Still the running issues remain.

Does anyone have any suggestions here. I've been working on this for a month and it's really got me stumped! It could be electrical, a sort of sensing issue on fuel delivery and return. The return fuel test is the most baffling to me...how it fixes the issue by blocking it. Maybe some kind of pressure issue...translating to bad sensing in the system?

Any thoughts are appreciated!

Cheers,

Simon

Simon

Sounds like a bit of a curly one
What town/city are you in?

We never got that car here - would assume it is probably the only one in Aus?
What motor is the 2.0L?
Was it the one used in the Mk 4?
Is it turboed?

You could also try here
http://www.vwwatercooled.com.au/forums/f128/

Bizarre wrote:Simon

Sounds like a bit of a curly one
What town/city are you in?

We never got that car here - would assume it is probably the only one in Aus?
What motor is the 2.0L?
Was it the one used in the Mk 4?
Is it turboed?

You could also try here
http://www.vwwatercooled.com.au/forums/f128/

Hi Bizzare!

Yeah it is baffling like I said. It's likely one of the only ones here I believe. I used to nip around Bristol, UK in it. I just thought seeing as I got a relocation package to come back to Oz, I'd bring her with me!

The engine is the 2.0 L 8V AGG, not turboed like the next generation. It's a cool little car.

Anyway, someone on Pistonheads has said 'I seem to recall having a similar issue on my mk3 8v GTI. The solution for me was replacing the relay I believe associated with the fuel pump which was a cheap and easy fix.'...so I'm going to check that out too.

Any ideas from your perspective?

CHeers,

S

"Any ideas from your perspective?"

Sorry make - was a 20 years air cooled Dellorto man

Now a T3 (T25 in your language) person
Whilst similar - i have not had much fault finding needs

Could it be due to blocked or 'sticky' or sticking fuel injectors? I have heard stories about such things (where fuel has gelled or is dirty, rusty etc.) & they can apparently be cleaned, if dirty, with a special solvent-circulating process, rather than replacing them. Thought of injectors as you said blocking the fuel return relieves the problem - perhaps due to the pressure increasing briefly so they work again?

Presumably they wear out and need replacing eventually anyway... Actually I had to have some replaced years ago on a ~15 y.o. motor, due to them being "worn out", but can't remember the symptoms.

I suspect your fuel pump is on the way out. It can't supply the required pressure when you ask it for a higher fuel flow (high load and revs). Blocking the fuel return reduces the required flow rate, thereby masking the problem. Your engine would probably be similar to the 2 litre that was fitted to mark 3 GL Golfs in Australia.

Fuel regulator.