Fuel Leak - 1.8t

[NC10]

Hi all,

Hoping someone on here will be able to help me.

I have 1.8t with quite a bad fuel leak. I've found the pipe where it's leaking from underneath the body near the fuel tank, but it's not connected to anything, see pic.

Should this be connected to something or is this an overflow or something, meaning I have a problem somewhere else?

Any help appreciated, cheers.

 

[DieselJake]

Looks like some form of breather or overflow or something to me but I'm sure someone with more of an idea will chime in.

I always think my car's have fuel leaks then realise it's my right foot that's the problem haha.

 

[NC10]

Sorry mate, only just seen this, thought I'd have got a notification or something. I need to pay more attention lol I started another thread on the same subject too so I might get told off

That's what I thought, but no idea where it leads too. Something must be blocked which is why it's leaking. Ive looked at every diagram on Google, even tried pushing it up into the engine but can't see anything.

 

[DrStrange]

Hi mate,

Im no expert but it seems that (as Jake Said) this isnt a connected pipe per se. Meaning, I think this is a breather pipe and is in its right place.

So are you certain this is where the fuel leak is coming from? Have you scanned the car? (Via ObD port)

A quick Google suggests its 99% the following;

Fuel pipe rubbing against chasis!!

Hope this helps

 

[odub]

Have you seen fuel coming from that pipe or could it be a problem with one of the others next to it?

 

[NC10]

Thanks for the replies.

Yes no doubting it's in the right place or anything like that, just need to know what it's connected to I suppose, so I can start to rule the causes out.

I think by putting "leak" I've probably under sold it lol The fuel is definitely coming from there and is under pressure, like an hose pipe really. I've lost a quarter of a tank just sat on the drive trying to figure it out. I turn the engine on and with maybe 5 - 10 seconds it's shooting out.

I've had someone tell me to change the fuel filter and carbon canister but not too sure on either of those myself.

I've tried tracing it back to the engine and it disappears up behind the front wheel and then I lose it.

 

[NC10]

The "leak"

 

[FlyingSparks5]

1 - Fuel supply pipe
From fuel filter
To engine
Do not kink
Press release tab on pipe connector to disconnect
2 - Fuel return pipe
From engine
Do not kink
Press release tab on pipe connector to disconnect
Clip onto fuel tank
3 - Breather pipe
Leading to activated charcoal filter in wheel housing (front right)
Do not kink
Press release tab on pipe connector to disconnect
Clip onto fuel tank

number 11 in the picture is the breather pipe

 

[NC10]

That's great mate thanks, I've looked at loads of diagrams like that but none that actually say what the bits are.

So the pipe is heading to the carbon canister then, near the front wheel, i thought it was at the back

 

[FlyingSparks5]

The diagram is actually from a 1.8T B6 chassis

 

[FlyingSparks5]

1 - Fuel supply pipe
From fuel filter
To engine
Do not kink
Press release tab on pipe connector to disconnect
2 - Fuel return pipe
From engine
Do not kink
Press release tab on pipe connector to disconnect
Clip onto fuel tank
3 - Breather pipe
Leading to activated charcoal filter in wheel housing (front right)
Do not kink
Press release tab on pipe connector to disconnect
Clip onto fuel tank
4 - 23 Nm
Secures fuel filler neck and earth connection → Item
5 - Overflow hose
Attach to wheel housing
6 - Rubber cup
7 - Retaining ring
8 - Seal
Renew if damaged
9 - Filler cap
Secured to tank flap
10 - Earth connection
To eliminate electrostatic charge
Installation position / test procedure → Fig.
Ensure that connector is seated properly and secure wire with securing bolt for fuel filler neck → Item
After installation, use an ohmmeter to check the electrical connection between the metal ring on the fuel filler neck and a bare metal part on the body. Specification: approx. 0 Ω
11 - Breather pipe
12 - Fuel tank
Removing and installing → Chapter
13 - Heat shield
For fuel tank
14 - 2 Nm
15 - Heat shield
For fuel tank
16 - 2 Nm
17 - Spreader clip
18 - Securing strap
Note different lengths
19 - 23 Nm

The full list

 

[NC10]

It doesn't actually show the line thats leaking on mine, that must be an overflow from the cannister, hopefully. Just glad of the clue saying number 3 heads up behind the front wheel.

Edit: there are 3 lines in that pic though, but they all seem to be connected to something don't they?

 

[FlyingSparks5]

If you give me your engine and gearbox code I will have a quick look to see if there is a different diagram for your chassis.

 

[NC10]

Out of those it would have to be No 2 because of the direction of travel??

So am I missing a piece?

 

[FlyingSparks5]

Number 2 is the fuel return pipe from the engine that will go back into the tank

 

[NC10]

Cheers mate. BFB is the engine, is that what you need?

 

[NC10]

Number 2 is the fuel return pipe from the engine that will go back into the tank

Out of the 3 lines, thats the only one traveling back isn't it?

Ones pure petrol to the engine, ones the petrol fumes to the carbon filter and the other is fuel back. Is that right?

 

[FlyingSparks5]

Quick check reveals as I suspected the two chassis B7 and B6 are the same diagram for the fuel lines

 

[NC10]

So I've lost a piece from the return?

 

[FlyingSparks5]

Line two does travel back to the fuel tank but it is a bit hard to understand how it has ended up disconnected from the tank. If you remove the rear seat bottom and then the inspection plates under the seat you should be able to see.

 

[FlyingSparks5]

 

[NC10]

I've left all my tools on site today so I will have to have a look tomorrow.

The pipe is well short of the other 2 so it is strange how it's become disconnected, especially from both sides, you would expect a piece hanging from one of the sides at least.

It's also completely different to the other 2 lines and I have noticed that some of the hose clips under the car are snapped. Previous bodge job perhaps?

Thanks for all the help anyway mate, appreciated.

I did scan the car as well in reply to the earlier comment, all clear. Only sign coming from the car is via the fuel gauge.

 

[FlyingSparks5]

Having just gone through the fuel delivery system I think you are on the right track. Can't be pipe one fuel to engine otherwise it would not run, pipe 3 is a breather to the charcoal filter, that only leaves pipe two - fuel return to tank.

 

[NC10]

I'll have a look tomorrow and get some pictures up.

Hopefully it's just a case of 're-bodging" it back up.

Do the diagrams you have show part numbers? Would be nice to completely re-do the entire return line, there's no way that return line can be standard when compared to the other 2. Surely they'd be the same, if anything I would have expected the carbon line to be as the return is.

 

[DrStrange]

Sincerely hope its the pipe your on track with.

Good luck.

 

[NC10]

Nothing under the back seat, just the top of the tank:

All 3 pipes seem to have made it back to the boot:

I just can't get in anywhere to have a decent look. If I remove the liner in the wheel arch, will that let me see in or is there something else behind it?

 

[FlyingSparks5]

Try disconnecting the return line from the tank and blowing down it, that way you may be able to establish whether the pipe has a break in it.
As always with pressure fuel systems be careful.

 

[NC10]

Do they just pull out?

 

[FlyingSparks5]

No they will have some sort of locking device on them as they are under pressure. Also have a look at this.
http://www.audi-sport.net/xf/threads/help-fuel-hose-disappeared.233525/

 

[FlyingSparks5]

This is what I use to release them if it gives you any clue as to how they clamp.

 

[NC10]

Exactly the same. Did the fuel filter sort it though??

I'm still edging towards the missing piece that a couple of posts mentioed. I may as well change the filter though anyway while I'm there.

There is no evidence of the pipe having a clip on though now I think about it. No marks or dirt build up etc I'll change the filter, see what happens.

Edit: Cheers mate, like a sprimg clip type of thing

 

[FlyingSparks5]

Don't know about the link I sent you I must confess I did not read the whole thread it was meant more on the angle of what the pipes do.
Best guess here and it is a guess as it is very difficult to make proper diagnostic without being in front of the car is that somewhere between the return from the engine and the fuel tank there is a break in the pipe (pipe 2) If you can get the return pipe of the fuel tank you should be able to establish whether that is the cause of your trouble.

 

[NC10]

Have a read, It's exactly the same scenario. I think he's got it wrong though saying it's an overflow from the carbon cannister now we know it's actually the return.

Do you know if anything is behind the wheel arch liner? No point wasting time removing it if I'm not going to be able to see anything.

 

[FlyingSparks5]

Sorry got dragged away, I am not sure whether you will be able to tell anymore by removing the liner, of the top of my head I don't thing it will help you.

 

[NC10]

Just on with the filter now, really struggling. Is the convertible the same as a saloon? I have a dirty big metal support running directly under mine, really can't see how it's going to come out without removing it.

 

[FlyingSparks5]

Assuming the car is not 4 wheel drive

 

[NC10]

Wow, that was enjoyable! That's something never getting changed again lol

Don't ask me how or why, but its solved the problem. Seems the other pipe is just an overflow and not the return line like I was thinking.

Thanks for all the input anyway, got there in the end. Now to clean her and go for a drive

 

[FlyingSparks5]

Stick with something and you normally will get there in the end.
Thanks for bringing the thread to a conclusion and posting the end result, gets a bit irritating and kinda little selfish when someone does not bother to let others know what the final outcome and solution was.

 

[fatihakar75]

I have same problem and i cant fix the problem ( 1.8t bfb multitronic b7)
Pls tell me what did u do to fixing leak?
Since 6 months i didnt find the solution
Pls tell me?

 

[Dave2304]

Hi did you ever find the fault on your b7