When refueling, the handle clicks after a few seconds without the tank being full. 

Unscrewing the tank plug, results in a big pressure release, not sure negative or positive. 

 

A mechanic disconnected both the carbon canister and the breather valve, but it STILL DID THIS!

So what may cause this annoying issue? Any ideas will get relayed back to the mechanic.

 

This can only be caused by the breather pipe.  If that's been disconnected at the top end, the problem must be the breather valve on the tank.  They're not available separately from the tank, and they're only accessible by removing the tank from the car.  It's probably not worth the hassle of trying to repair.

I would also recommend reconnecting the charcoal cannister pipe if that's just been left open.  It could be venting fuel vapours to atmosphere and causing a fire risk.

1 minute ago, TomsFocus said:

This can only be caused by the breather pipe.  If that's been disconnected at the top end, the problem must be the breather valve on the tank.  They're not available separately from the tank, and they're only accessible by removing the tank from the car.  It's probably not worth the hassle of trying to repair.

I would also recommend reconnecting the charcoal cannister pipe if that's just been left open.  It could be venting fuel vapours to atmosphere and causing a fire risk.

He disconnected it from the canister, not from the top. That's what he suggested also. When/if the fuel pump ever fails, it'll be a good opportunity to check the other parts since the tank will be detached from the vehicle. 

The pipes were connected after the tests. I now just have to use the non-sealing tank plug the car came with when I got it. Each time I open the little door, it smells like fuel in there. I don't think this is safe either though..

I want to add some details because i'm perplexed. 

The mechanic used pressured air to test the line between the canister and the tank, and the tank seemed to inflate a bit, meaning that the line is unabstructed. If that's the case, how come when I drove the car for 10 minutes and went back to check, it still depressurized as soon as I unscrewed the cap? It should've breathed from the unplugged tube between tank-canister. But no, It still did the effect. 

Is there a switched valve on the tank itself?

19 minutes ago, ntelas said:

I want to add some details because i'm perplexed. 

The mechanic used pressured air to test the line between the canister and the tank, and the tank seemed to inflate a bit, meaning that the line is unabstructed. If that's the case, how come when I drove the car for 10 minutes and went back to check, it still depressurized as soon as I unscrewed the cap? It should've breathed from the unplugged tube between tank-canister. But no, It still did the effect. 

Is there a switched valve on the tank itself?

Hmm, that one's got me confused as well... 🤔

I believe both the canister line and the breather line have manual valves where they attach to the tank.  There are no electrical connections to them, so not switched as such.

The charcoal cannister valve 'should' only allow air (and fuel vapour) to be sucked out.  I'm a bit surprised the compressed air could make it go the 'wrong' way but have never tried it.

The breather valve may work both ways.  Allow air out while the tank is being filled with fuel.  Then pull air back in as the tank slowly drains to stop negative pressure being created.  (But if this was true, the tank shouldn't have inflated with compressed air)

I'm afraid I don't have any way to confirm those thoughts at the moment.

Are there 2 separate air tubes? Just so I understand right. Because I have never seen a tank in my life. If that's the case then I understood his trials wrong and what I said about the air pressure test is wrong.

1 minute ago, ntelas said:

Are there 2 separate air tubes? Just so I understand right. Because I have never seen a tank in my life. If that's the case then I understood his trials wrong and what I said about the air pressure test is wrong.

Yes.  There is a small hard plastic tube for the charcoal canister.  And a slightly thicker rubber tube for the breather pipe.

If you can see eBay UK links this one shows it well.  Ignore the very large tube on the side, that is the filler.

https://www.ebay.co.uk/itm/266632643776?

 

(Note, there are two connections for the charcoal canister, but they simply join the tank together, so they can always suck vapour from the 'empty' part when fuel moves one way or the other under braking or accelerating or up and down hill etc)

mines done this from new .BUT only at a bp pump ..every other petrol station has been fine ..i get around it by not pushing the nozzel in too deep and yes sometimes i get a woosh of air from the tank ..depends how empty it is .. never bothered me

1 minute ago, ferretfloozy said:

mines done this from new .BUT only at a bp pump ..every other petrol station has been fine ..i get around it by not pushing the nozzel in too deep and yes sometimes i get a woosh of air from the tank ..depends how empty it is .. never bothered me

That's interesting. As big of a whoosh as the one on my video clip? Mine sounds so bad that you can hear the tank move down there. There it was 1/3 full, but even now that it's at 3/5 it still does it if I use the normal plug.

Mine has had the whoosh of air as long as I have had the car. It can also be difficult to fill. This seems to happen randomly and not at any particular petrol station.

How easy is it to access the breather pipe at the filler neck end?

Is it worth changing the vapour canister? The bolts holding it to the sub frame look difficult to remove. Access is difficult and they are rusty. The new canisters are also £75 or more each.

13 hours ago, AntonovAN12 said:

Mine has had the whoosh of air as long as I have had the car. It can also be difficult to fill. This seems to happen randomly and not at any particular petrol station.

How easy is it to access the breather pipe at the filler neck end?

Is it worth changing the vapour canister? The bolts holding it to the sub frame look difficult to remove. Access is difficult and they are rusty. The new canisters are also £75 or more each.

In around a decade of working on cars, I never had to replace a single charcoal cannister.  I don't remember seeing anyone else replace one either.  I suppose they could get blocked in theory but it can't be a common issue.

The top end of the filler breather should be accessible by removing the wheel arch liner on that side.

Thanks for the reply.

Is part number 9G271B the breather hose that may be blocked?

https://ford.7zap.com/en/car/43/no/20/1556/15499/67593/#9G271B

That isn't a breather hose.  It's an emergency vent that won't be used unless there's an issue.  I'm not even sure if it'll be fitted to UK cars as it's illegal to vent fuel/oil vapour to atmosphere over here.

Thanks for the reply.

What does the breather pipe actually look like?

I recently posted a video showing how to remove the petrol cap lock mechanism.

All I can see in the video are two stainless steel pipes. Is the problem caused by the smaller pipe being blocked?

Looking at some on ebay, the smaller pipe is welded to the side of the filler neck at the top end.

13 hours ago, AntonovAN12 said:

Thanks for the reply.

What does the breather pipe actually look like?

I recently posted a video showing how to remove the petrol cap lock mechanism.

All I can see in the video are two stainless steel pipes. Is the problem caused by the smaller pipe being blocked?

Looking at some on ebay, the smaller pipe is welded to the side of the filler neck at the top end.

My apologies, I confused myself last night.

You are right about the 3rd charcoal canister pipe.  It does act as a vent while filling and should also allow air back in as the tank level drops.  This is a Mk3 filler but looks the same as Mk2, with the bent plastic line being the one from the charcoal canister.  If you disconnect the other end, you could try blowing through it to check if it's clear.  There may be some dead insects in there if not.

ford focus 1.6 petrol fuel filler neck 2011 - 2014 | eBay

 

The smaller metal pipe is the main breather to release large amounts of air while filling.  It would take ages to fill with only the tiny pipe releasing air.  But as that one exits behind the filler cap, may not allow any air back into the tank from outside as the level drops.  (Having said that, I'm not sure whether the filler cap has a two-valve on it - my Focus's were all the capless EasyFuel system).

There are some 'mechanical' vents on top of the tank for both the evap pipes and the large breather pipe.  They use springs and/or floats to close the pipes when the tank is very full, and should open again as the level drops.  You may find the large filler vent is stuck closed if the problem isn't with the evap system.  Sadly that's not accessible without dropping the tank.

On 6/17/2024 at 1:06 PM, ntelas said:

When refueling, the handle clicks after a few seconds without the tank being full.

I'm curious if for the OP this was a one off incident? Few weeks back whilst on holiday, I filled up at a garage never used before. After every 4 or 5 seconds, the handle clicked and stopped the pump. After a couple of minutes, I got bored trying to full her up, paid for the few liters I took, and left.

Since home, I have used my normal garage twice, filled to the brim, no issue. Obvioudsly something faulty with the initial garage petrol pump...

16 minutes ago, StephenFord said:

I'm curious if for the OP this was a one off incident? Few weeks back whilst on holiday, I filled up at a garage never used before. After every 4 or 5 seconds, the handle clicked and stopped the pump. After a couple of minutes, I got bored trying to full her up, paid for the few liters I took, and left.

Since home, I have used my normal garage twice, filled to the brim, no issue. Obvioudsly something faulty with the initial garage petrol pump...

The incident mainly happened at the same fuel station. Because the car runs LPG, I very rarely have to fill petrol.

3 minutes ago, ntelas said:

The incident mainly happened at the same fuel station. Because the car runs LPG, I very rarely have to fill petrol.

Have you tried another fuel station? (I miss LPG, a previous car I had ran brilliantly on it!)

10 minutes ago, StephenFord said:

Have you tried another fuel station? (I miss LPG, a previous car I had ran brilliantly on it!)

Yes it did it on another one as well. But recently I filled at another just for 6 liters and it didn’t do it. I don’t know if it’s the quantity or the station. I don’t use this car anymore and it’s for sale. 

7 hours ago, TomsFocus said:

If you disconnect the other end, you could try blowing through it to check if it's clear.  There may be some dead insects in there if not.

Thanks for the reply.

I notice that it is connected to the canister with a plastic clip fitting. I read on another thread that they can become fragile and break when released.