I have a 93 40 hp evinrude. will start at the launch and run fine. Shut it off to do some fishing and when I go to fire Up the outboard it only cranks and will not fire. Seems almost like it is not getting fuel.? The next day it fires right up. Now yesterday couldn't even get it fired up at the launch. Its driving me crazy. I'm not much of a mechanic. I've had the boat for 5 years and have never had this problem. It had a spring tune up this March. took it back to the shop with above problems and of course it started every time for them. suggestions...?