When I remove my fuel cap there is a loud sucking noise, should the tank have a breather, if so does anyone know where it is to save me riping the insides out of the car.
I think this could be causing a misfire which only seems to happen when the tank is full, or nearly empty.

Thanks in advance

Andy

 

Andy,

all Imprezas do this when you open the fuel filler cap. Nothing to worry about, and is probably a designed safety feature to prevent fuel vapours escaping from the fuel tank.

Mine seesm to make the same amount of noise regardless of how empty the fuel tank is when opening, and if there was no breather mechanism, then by the time you had used 1/3 of a tank, the vacuum would be so great that you wouldn't be able to pump out any more fuel, and if you could the tank would probably collapse under the pressure!