Breathing troubles

[leafspring]

On my '94 Nissan Sunny snotter, the petrol tank breather isn't... breathing
Unscrew the cap and your greeted by a hiss reminiscent of opening a coke bottle.

My Google-Fu has failed me... Can someone tell me where the filler/tank breather pipe is hidden before I start removing the wrong trim panels and snapping clips?

There isn't a breather in the Nissan stamped (original/OEM) filler cap but there is a breather type hole outside the filler neck. As far as I can tell this end is clear

(I only bought it on Saturday and the Haynes manual hasn't arrived in the post yet)

[Chromed]

Well, it could be completely normal . I've had cars that do that with no problems.

[leafspring]

Reading the owners hand book it doesn't say anything about a suction/hiss when removing the cap.
However it does say to only use the correct Nissan cap as it has a safety valve and is part of the emissions control system (something like that).

Never know a car to do it before though

I need to find another Sunny owner to tell me if its normal.

[fatjon]

It's normal on all modern emission controlled cars. On some it's a major hiss on others the tank vacuum is so low that you hear nothing. It's to ensure that no fuel vapor leaks out of the tank and kills trees and bunnies.

[leafspring]

[Locknut]

It's a 94 car so I'd say it has a closed breather system with a charcoal cannister. This means that the fuel tank is not allowed to breath fumes to the atmosphere. Instead the tank breaths through a charcoal cannister usually located in the engine compartment. The petrol fumes are captured by the charcoal cannister and not allowed in to the atmosphere. The cannister is connected to the inlet manifold and when the conditions are suitable the fumes are drawn into the engine and burned off. All this is controlled by valves and hoses. The hiss when you open the tank is completely normal.

[leafspring]

Locknut said:

It's a 94 car so I'd say it has a closed breather system with a charcoal cannister. This means that the fuel tank is not allowed to breath fumes to the atmosphere. Instead the tank breaths through a charcoal cannister usually located in the engine compartment. The petrol fumes are captured by the charcoal cannister and not allowed in to the atmosphere. The cannister is connected to the inlet manifold and when the conditions are suitable the fumes are drawn into the engine and burned off. All this is controlled by valves and hoses. The hiss when you open the tank is completely normal.

Thank you.

Modern cars the sooner I have another Series Land Rover the better

[beko1987]

My Puma used to airlock the fuel cap on sometimes, had to quickly fire her up, blip the throttle then let the revs drop right down and the suction would be released.

Was a pain on a very hot day!