Fuel Pumps changed but still jumping

[lozza976evil]

Hi,

 

New to this and by no means technically minded when it comes to cars and repairs.

 

I have an Octavia 1.9TDi. It's 2008 plate. Been well looked after from new and always serviced regular with MobilOne oils. However, this past year the car developed a surge or should I say a choke when travelling at around 55-60 mph in top gear. When I put my foot down to give me a little bit more power the car begins to struggle for fuel and lunge and jump (spit and fart).

 

So taking it to VW they couldn't find the issue but said it could be the fuel pump in the back. They quoted me daft price so went elsewhere. A really good mechanic friend who works for ariva bus firm as a fitter, replaced the back pump and found it was starting to get covered in engine oil which he said was a byproduct of the high injector fuel pump which is attached to the engine. Hey-ho, just had that pump replaced and there was quite a lot of engine oil getting mixed with the fuel. So thought the problem would have been fixed, but low and behold on way back home the car still continues to struggle for fuel when your either cruising in top gear at around 55-60 mph and go to put your foot down, or when your at low speeds in a lower gear such as 2nd and then go to pull away by putting your foot to the floor and the car just spit and farts and doesn't seem to want to give you the fuel.

 

VW said they couldn't find the issue. I've recently had the ECU unit changed which cost me a fortune just for the labor so I know it couldn't be that, but just wanted to ask people out there if they have experienced this issue in the past and if they know what it could be?

 

There's nothing else wrong with the car and I'd hate to get rid of it. Body work is sound and it's just had a new clutch, ECU, discs and brakes and should last another 4-5 yrs. Unless I can solve this problem it could be a scrap yard :(

 

Any advice would be really appreciated.

[softscoop]

Could be veins in turbo sticking closed. That will give you the symptoms you describe.

Also when was the fuel filter last changed?

[Phil-E]

Which pump was it? The tandem pump on the side of the engine?

 

Has the fuel filter been replaced?

 

Phil

[lozza976evil]

Yes. The filter that sits on the side of the engine was changed today and the filter that is attached to the fuel tank was also changed. As for the fuel filter, I will need to investigate that in my service records. Would a simple blocked filter cause such an issue?

As for the turbo suggestion, would that cause the turbo to lag all the time? Because when the cars pulling hard it doesn't lunge like it does when I'm at cruising speed then go to put my foot down.

Thanks for the replies btw.

[cheshire_cat]

I would think once you had a new fuel filter   you need to check for fuel (rail) pressure at the tandem pump   from memory approx. 7 bar     a starting place before getting into the complex (expensive) stuff

[lozza976evil]

The tandem pumps already been changed along with the pump which is attached to the fuel tank. I've yet to have the fuel filter changed which was done October 2013, but seems as tho the spitting and farting happens in any gear when the revs are around 15-17 thousand and you go to gain more fuel/power by putting your foot down.

If the filter doesn't solve the issue what are the next steps? Injectors? Sensors? It seems an expensive trail and error process at the moment.

[Phil-E]

A blocked filter or air getting into the fuel system cause a surging.

 

There can be problems with the wiring loom for the injectors than can cause some irregular running. The wiring becomes brittle and cracks as it runs inside the engine.

 

Phil

[softscoop]

Is there a load of smoke out the back when it does it?

[cheshire_cat]

the filter should have been changed with the pumps-----don't assume the T pump is good until the delivery pressure has been verified  it wouldn't be the first faulty new Item  then check pneumatics and turbo freedom of movement and move to wiring as above    have you had it scanned?  

[lozza976evil]

No smoke comes out the back. Just a real hard lag in fuel that makes the car spit and fart. It doesn't do it all the time however, just at lower revs.

I've been doing some research and by no means technical minded at all when it comes to these things, but some people are stating things such as the HPFP sensor and the fuel pressure regulator... what are these and could these cause such a problem?

how would I go about getting this scanned? Would the dealership have to do this? They only seem good at failing to identify problems and taking my money.

[Phil-E]

I think rather than getting carried away and thinking all sorts of possibilities, start simple.

 

Get the fuel filter changed make sure there is no diesel leaking out around the seal and there is no air in there. More often than not it's just as simple as the seal on the fuel filter not sealed properly and it lets air in.

 

If that doesn't cure it then it was worth a try and probably needed changing anyway.

 

Why was the ECU changed BTW?

 

And have you had it hooked up to diagnostics?

 

It might be worth finding someone with VCDS and a laptop to do some live logging while it's doing it checking boost and fuel pressure etc to try and pinpoint the problem.

 

Phil

[lozza976evil]

Couple yrs back the car started jumping like it is now. Dealership couldn't find the issue and it wasn't being registered in the diagnostic. After months and months of it getting worse the car kept lunging and I got loads of lights on the dash such as the coil and engine oil pressure light. So when I took it back in they identified the ECU the issue. After that it stopped jumping. Few months later began again so I thought it might be the same issue. Apparently not according to the dealership.

So I'm now trying to work my way through the fuel system trying to find the problem. This morning the car gagged and my coil light came on. The cars full of surprises at the moment :/