Australian Car Repair Issues? Ask an Auto Mechanic for Answers ASAP
Any pressure that builds up in the tank is supposed to vent out through the carbon filter, which has a filter after it as well. Typically if either of these get clogged up, you will build pressure, but it will also be next to impossible to fill up the fuel tank because fuel will come back up the filler neck and shut off the pump.
Is this what you are talking about?