Small Engine Troubleshooting Problems? Ask a Mechanic Now.
It sounds like you have a connection that is not made well.
All fitting should be sealed with a tape or putty that is rated for gas use. I personally use a PTFE tape (putty gets too messy).
Check to make sure all fittings are properly sealed, and snug.
You will have to shut the gas off first.
Then take apart the leaking joint, clean it up, reseal and retighten it.