2002 50hp mercury wont start in water but will out of water

flsnookhunterflsnookhunter Posts: 193 Deckhand
Ok, so I have had my 16' boat with 50hp mercury in Orlando at the shop for complete tune up and took it out up there and it ran great. I brought it down to South FL and went to take it out and engine just keeps cranking and will not turn over. When I start it with the muffs on out of the water it starts right up first try. Any Ideas? I tried 2 days in a row and same thing happens. Starts right up on the muffs but will not turn over when I put it in the water. Also will take any suggestions of affordable mechanics around the Delray/Deerfield area. Thanks


  • OneTimeOneTime Posts: 42 Deckhand
    Won't turn over or won't start?

    The motor starting right up on the muffs and then not even turning over(starter not engaging) in the water a few minutes later makes no sense.

    Carbed motor?

    Tilting the motor way up while trailering to the ramp?

    It has to be something happening on the way to the water.
  • snookaffinitysnookaffinity Naples, FLPosts: 997 Officer
    If there is low fuel level, the position of the boat could prevent gas getting to the fuel pick up in the tank :shrug:huh
    "It is better to keep your mouth closed and let people think you are a fool than to open it and remove all doubt." - Mark Twain
  • SUPER DSUPER D Posts: 639 Officer
    This happened to me with a 30 HP two stroke Johnson. It acted like it was flooded, would start on the muffs but not at the ramp.
    Turned out to be a blown head gasket. With in water, it let more water in the exhaust housing, and or added back pressure. On the muffs
    has no back pressure , and excess water runs out prop. I ran on muffs, then pulled plugs, and saw water on both plugs. Good luck.
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