Check for water or trash in the float bowl. Check fuel flow with float and needle by moving the float up and down with your finger, make sure it's cutting off and flowing etc. Squirt out the main pickup jet while you've got the bowl off. Could be a piece of foreign material blocking fuel flow to the needle, or a blockage in the pickup tube. When you let it sit for a while, it will move off the inlet, but sooner or later it will go back over the inlet going to the needle and bowl and starve for fuel again. Hope this helps.