gas tank

IM HAVING TROUBLE GETTING GAS TO NFLOW OUT THE PETCOC. i installed a new one and checked the filter fine checked the gas cap vent fine but IT STILL TRICKLES OUT . I GET A WHOOSHING SOUND LIKE THERES A LOT OF PRESSURE BUILDING UP WHEN I OPEN IT. DOES ANYBODY KNOW WHERE TO GET NEW RUBBER GASKET THAT GOES AROUND THE VENT INSIDE THE GAS CAP IT IS QUITE WORN ? ANY IDEAS?

The gas tank has a vent in the cap. Sounds like your vent may be plugged.
You can check it by opening the gas cap, and see if that fixes the flow.