Hi,
while watching YouTube videos I have been trying to figure out whether I have a blockage in my emission control system (EVAP). I was able to take apart the fuel vapour hoses that go to and from the charcoal canister. Pumping air through the canister works, i.e. air moves through. I have no problems with the control solenoid either.

Q1 - the metal pipe that feeds into the charcoal canister, where does it come from? (gas tank or fuel cap?)

Q2 - if I pump air into the metal pipe, should it flow freely or not? Can this tell me if there is blockage?

I found a nice picture made by Ziggy122 https://www.fiatforum.com/punto-mk2...ing-fuel-filler-flap-gars3.html#content_start
that shows there is a bendy tube under the fuel filler cap. Is this where the fuel vapours are coming from and going to the charcoal canister?


Thanks for your help,
Conrad

That bendy tube is the tank vent while filling
Its meant to allow vapour to escape while filling.... however like all puntos.... its crap..... most people just stick fuel nozzle in at an angle to allow to escape....

Iirc the charcole canister is just a store of fuel vapour from the tank
The vapour is used during induction stroke to be burned instead of been just vented....

I dont think the punto has an evap system thats monitored, never really played with it much as its never broke on either puntos ive had...

Tbh the fuel system is a solid rock.... never a murmer....

Ziggy

Hi Ziggy,
I also don't think the EVAP is monitored because the car starts no problem with the tubes disconnected.
But, still would like to know whether the bendy tube eventually turns into the metal tube that goes into the charcoal canister. If so, it means it should not be blocked... and if I can unblock it, I might improve my time at the fuel pump!
Conrad

Reading through the old posts here it appears the new puntos did not have this filling problem?



Is it happening because the filling pipe is being crushed by the mudguard?

YellowPuntoFiat said:

Hi Ziggy,
I also don't think the EVAP is monitored because the car starts no problem with the tubes disconnected.
But, still would like to know whether the bendy tube eventually turns into the metal tube that goes into the charcoal canister. If so, it means it should not be blocked... and if I can unblock it, I might improve my time at the fuel pump!
Conrad

Click to expand...

I suspect it goes back to towards the tank as its the only source of fumes....

Puntos are just plain little bitches when it comes been at the pump im affraid....

judderbar said:

Reading through the old posts here it appears the new puntos did not have this filling problem?



Is it happening because the filling pipe is being crushed by the mudguard?

Click to expand...

Mk2b dont have mud guards at all on rear archs or bumper.... and it still exsists as a problem

Grande onwards is corsa

Ziggy

Ziggy122 said:

..Mk2b dont have mud guards at all on rear archs or bumper.... and it still exsists as a problem

Grande onwards is corsa

Ziggy

Click to expand...

I was thinking of the wheel arch cover/liner/mud guard


https://www.onlinecarparts.co.uk/prasco-7455828.html

judderbar said:

I was thinking of the wheel arch cover/liner/mud guard


https://www.onlinecarparts.co.uk/prasco-7455828.html

Click to expand...

Mk2b didnt get any of that either....

Ziggy

Ziggy122 said:

Mk2b didnt get any of that either....

Ziggy

Click to expand...

OK you keep saying that but I have one on my car so there!





Are the petrol filling pipes of UK cars really exposed to the stones flying off the tyres??


If so, no wonder you guys have rear wheel arch rust problems.

Ziggy122 said:

Puntos are just plain little bitches when it comes been at the pump im affraid....

Ziggy

Click to expand...

Tell me about it, clicky click click when filling, so frustrating. I generally end up stopping at £15 cos I can't be bothered standing there any longer. I'm sure people must think us Punto owners have 100 litre tanks!

YellowPuntoFiat said:

Hi,
while watching YouTube videos I have been trying to figure out whether I have a blockage in my emission control system (EVAP). I was able to take apart the fuel vapour hoses that go to and from the charcoal canister. Pumping air through the canister works, i.e. air moves through. I have no problems with the control solenoid either.

Q1 - the metal pipe that feeds into the charcoal canister, where does it come from? (gas tank or fuel cap?)

Q2 - if I pump air into the metal pipe, should it flow freely or not? Can this tell me if there is blockage?

I found a nice picture made by Ziggy122 https://www.fiatforum.com/punto-mk2...ing-fuel-filler-flap-gars3.html#content_start
that shows there is a bendy tube under the fuel filler cap. Is this where the fuel vapours are coming from and going to the charcoal canister?


Thanks for your help,
Conrad

Click to expand...

Conrad, have you made any progress finding a solution yet?


I have also just been looking at youtube videos on the evap systems and the common problem of a fuel tank not filling in a variety of different cars.


As far as I can tell the bendy tube mentioned by you and Ziggy is the drain pipe from the holes near the internal flap just inside the petrol cap


I am going to have a look at my fuel system today and see what I can find out. At the moment everything is hidden behind the mud guards.

judderbar - my son said that it filled 'easier' the last time he went to the pump but he wasn't able to fill it yet (i.e. got progressively more difficult). My explanation though is that I may have realeased some air out of the EVAP hoses when I disconnected the fuel vapour lines to the charcoal cannister.


If the bendy tube is the drain pipe, then it's not the solution.


I would definitely appreciate if we can figure out where the metal tube from the charcoal canister goes and whether it should be unblocked when air is pushed through. But my understanding of the system is that it should allow air through. If this is the case, then the next problem will be to figure out how to clean the tube and see whether this fixes the problem.


Thanks again for your help,
Conrad

YellowPuntoFiat said:

@judderbar - my son said that it filled 'easier' the last time he went to the pump but he wasn't able to fill it yet (i.e. got progressively more difficult). My explanation though is that I may have realeased some air out of the EVAP hoses when I disconnected the fuel vapour lines to the charcoal cannister.


If the bendy tube is the drain pipe, then it's not the solution.


I would definitely appreciate if we can figure out where the metal tube from the charcoal canister goes and whether it should be unblocked when air is pushed through. But my understanding of the system is that it should allow air through. If this is the case, then the next problem will be to figure out how to clean the tube and see whether this fixes the problem.


Thanks again for your help,
Conrad

Click to expand...

Working on the car at the moment but I made a bit of progress so far........



I traced the tube from the front canister. Under the front seats it changes to a blue plastic pipe that goes to the top connection of a check valve arrangement just under the filling cap. However between the check valve and the height of the sill it becomes a black plastic pipe and there is a quick release fitting at that position. The other two connections from the check valve arrangement are slightly lower and are black either side of the quick release fittings in that area. These black pipes must go to what I think is two separate check valves on the top of the tank.


I connected the 'check valve arrangement' to the petrol pump and pumped some petrol through. Once the petrol reached the valve I got 2 bar so I waited for that to fade away but when I moved the 'check valve arrangement' (connected to the filler cap contraption) the pressure released. The 'check valve arrangement' might be a crash/roll over check valve and/or to prevent fuel from getting to the canister.



However at the end of it I dont get a very good flow of air through that 'check valve arrangement' coming from the direction of the tank. It flows but is not very impressive.



The quick release fittings have two white plastic tabs/buttons which I worked with a bit of light oil to clean the crud off before they will would go fully in.


Ziggys small flexi pipe is just dangling there to allow water or fuel outside the cap to drain.


The two cm diameter flexi hose is lower than the tank connection before it bends up to the 'filler cap contraption' so it was full of petrol. It seems to be designed to not allow air to flow out of the tank unless the tank is empty - hard to work out exactly what it is supposed to do. Further up it has a chamber for petrol air separation. I am going to try and pull this flexi pipe a little higher and tie it to see if it makes any difference. The immovable rigid connection it fits to is already quite low however.

So I did my best to clean up the filler pipe roll over valve/canister protector by washing petrol thru it and even washed it thru with hot water. No change. I then dried it with an air pump by pulling air thru from the petrol tank to the engine compartment and it is better.



What we need is a volunteer to destroy one of these filler pipes so we can see what is inside that valve.

flisko do you have one of these punto filling pipes lying around some place?


I think you can lever up an edge of the valve and twist it out. It is not a screw out valve.

can smash one open tomorrow to see whats in

flisko said:

can smash one open tomorrow to see whats in

Click to expand...

:slayer::yum::worship:


If you can recover the valve intact and see how it is supposed to work it will be very helpful. If I know how the valve is supposed to work I can make sure I can get another working filler pipe.


I am assuming we should be able to suck on the tube on the valve and easily get a flow. I get a very poor vibrating flow from my valve.

judderbar said:

:slayer::yum::worship:


I am assuming we should be able to suck on the tube on the valve and easily get a flow. I get a very poor vibrating flow from my valve.

Click to expand...

You are still talking about the petrol filler now right?
If not, I'd advise a trip to the doctor!

nitramtpr said:

You are still talking about the petrol filler now right?
If not, I'd advise a trip to the doctor!

Click to expand...

Maybe I need a Doctor because I am still talking about this filler hose valve!


I am supposing a Fiat tech will know the purpose of the valve and how to test it. What it should and should not do.


What about autodata? flisko

judderbar said:

So I did my best to clean up the filler pipe roll over valve/canister protector by washing petrol thru it and even washed it thru with hot water. No change. I then dried it with an air pump by pulling air thru from the petrol tank to the engine compartment and it is better.



What we need is a volunteer to destroy one of these filler pipes so we can see what is inside that valve.

@flisko do you have one of these punto filling pipes lying around some place?


I think you can lever up an edge of the valve and twist it out. It is not a screw out valve.

Click to expand...

that valve what you are pointing with the finger right?

flisko said:

that valve what you are pointing with the finger right?

Click to expand...

That's the one.



Does Auto data have any test procedures for the evap system on the punto mk2b?

Believe it or not that valve is listed on the forum Eper and is available from Fiat! # 46537951


But how to fit such a valve??




The valve is not being sold with the required gasket and Eper is not showing one is required.. On my car this gasket may be a grommet that has become very hard. Looking at the underneath of the new valve in the picture it is not obvious how the gasket/grommet can be fitted to allow the valve to handle a few bars



Perhaps the dealer can tell me what the valve should do and how to test it??



Otherwise I am inclined to cut out the current valve, find out what the problem is and plastic weld it back in place