Replace all your rubber lines. Not that expensive and not that hard. When the original rubber lines (they have the cloth outer wrap) start to go, they leach air in when running and leach fuel out when stopped. Make sure you include the line with the threaded peice that comes out of the tank. I just ran the tank low on fuel then drained what was left into a bucket.
I've done this to both the benzes that I've had, both were beginning to drip below the tank. I noticed I went from some bubbles in the primary filter to none after the job was completed, plus no more leaks
