Can you explain exactly how you do this, please?
IIRC, on every motorcycle, outboard, generator, & snowblower I have had, which amounts to about 25 items, there has been a screw or bolt located at the bottom of the float bowl. Loosen until no more gas flows out after a shake or two. Some drain screws/bolts are right in the open, some are kind of hidden.
Older cars with carburetors, if any are left, should also be drained, same locations as above, if not driven every week or so.
If your motor is in a well, or way out there on a transom bracket, the drain screw may be a bit difficult to get to. So the next best thing is to "run it dry", even though there will be a small amount of fuel left in the bowl. If you back the screw all the way out it is guaranteed it will fall in the water.
I have used this for many years and have had no fuel related problems except for one time I forgot to drain over the winter, which was my fault. No affiliation with Berryman's, other additives may work as well or better. Maybe they aren't even necessary, your mileage may vary.
Fuel Additives / Treatments | Berryman Products