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Alfa Nutter · Posted: Wed Apr 21, 2004 10:51 am Post subject: Fuel Tank

Greetings

i am new to this site,maybee you lot can help me?

Does anyone know where the petrol tank breather pipe is?And is it easy to unblock,i ve been unable to look because of bad weather.

I,ve been told thats why my car is running not quite at its best.I tested this by removing the fuel filler cap and going for a blast,and sure enough she kicks like this Smile

apparently its something to do with the air pressure in the tank,and it must be able to breath.I reccomend you guys try it.

Any advice would be apprecated so i can get back to pasting Saxo VTR/VTS with ease.

thanks!
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Sportwagon 16v series 3 with a touch of zender

GaryUK · Guest

The breather pipe runs up alongside the filler neck in the wheel arch it's attached with plastic clickey ties (12inch) so buy some before removing it or if you are patient then release them(I can never be bothered). If the end isn't blocked then there is a valve midway along, this may be the culprit.

bobbber · Posted: Wed Apr 21, 2004 2:07 pm Post subject:

Oops! I wondered why when I undo the petrol filler cap it hisses at me like a snake!

Thanks, I'll try it!

Rob
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Fiat Bravo 165 Sport

Alfa Nutter · Posted: Wed Apr 21, 2004 2:53 pm Post subject:

Thank Gary,just like my fiat strada 10 years ago. Wink

Rob let me know if it works for you too.

cheers
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Sportwagon 16v series 3 with a touch of zender

Guest · Guest

I have also been having some rough running problems - my fuel tank hisses when I take off the cap too, so after reading this thread I checked out my breather pipe.

When I removed the check-valve I got the same hissing from the end of the pipe when the pressure equalised. I tried driving a short distance with the valve out, but unfortunatly the car was still the same - but thats another issue.

However I am still curious about the breather though. Is some hissing normal? Can anyone tell me how the breather system is supposed to be routed (The car has had a new fuel tank so I would like to check it is correct)

Guest · Posted: Fri Apr 23, 2004 9:14 pm Post subject:

Hello,again

Tought you may be interested,that when i checked the valve[breather] it was actually installed the wrong way around!So it was not letting any air out.I wonder if it left the factory like this?Because there is no evidence of tampering.If so then yours could wrong too.You can test the valve easily by disconnecting it first and blowing and sucking on it [oh er!] this will tell you which way round it should be.My pipe from valve to external atmosphere was blocked with spiders eggs too.

A guest asked where it was routed.It runs from the internal top of the filler fat pipe,down to the tank [hidden behind main pipe as its very skinny] to the tank.And the actual valve is paralel with the tank at the back of the tank.Not hard to find once you are under the car.

Hope this helps

Marcin · Posted: Mon Apr 26, 2004 10:24 am Post subject:

Dave (Minari) · Posted: Mon Apr 26, 2004 5:51 pm Post subject: Re Fuel Tank

All.
I had hoped some one would give a really good answer to this one. So I will try.
The check valve is there to stop fuel coming out should someone put their car on its roof. The pipe with the check valve is there to prevent the fuel pump causing a vacuum in the tank, and stopping the flow of petrol.
Therefore the check valve should permit air to go into the tank, but make life difficult for petrol to flow out.
Of course one doesn't want the tank to form really high pressure in the event of a fire. so the valve will permit an escape of vapour or fuel.
If the check valve (and of course, the petrol cap) stopped all vapour/fuel coming out, in the event of a fire you could end up with a BLEVE. This is a Boiling Liquid Expanding Vapour Explosion, where the pressure builds up until the tank can take no more and will let go with a disasterous explosion. This phenomen well known in fire fighting circles, and has caused a number of fire deaths with road and rail tankers in the past.
So the chech valve is important.
The hissing when you remove the fuel cap shows that things are fairly OK. The Workshop Manual says if the vavle doesn't permit air flow into the tank without resistance, and out of the tank with some resistance, replace it.
Sorry if that is a bit technical, but I hope it helps.
Dave.
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Retired and working harder than when employed!!! Crap at golf- "Stupid Bl**dy game!"

Guest · Posted: Mon Apr 26, 2004 9:50 pm Post subject:

Thanks,Marcin and Dave.

Better put valve back as it was before i explode!! Embarassed

Guest · Guest

Thanks from me too.
I looked mine over and it all seems to be in order.