I have a 1993 Mercury 115. It starts up right away when I first get to the lake and runs great. If I try to start it back say within 5 minutes usually no problem but it sits for about 30 minutes it will not start. I can sometimes use the throttle lever to get it going but it will usually go dead when I put it in gear. This happened again this past weekend. By the time I got home, which was about a 2 hours drive, it would start again. Any ideas on what my problem may be? Thanks in advance.