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Fuel Smell Mako 238 1984

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  • Fuel Smell Mako 238 1984

    I smell gas fumes coming from the bilge area in the rear of the boat. I have changed all hoses and gasket to the sending unit at the front of the tank but still have the smell. My next step is to change the fuel line which runs from the outboard to the tank even though I changed it about 4 years ago.

    I do not see any gas in the bilge...just water. Generally the only time I smell the fumes is when I'm underway putting a load on the engine which I would imagine is creating some sort of pressure in the gas tank and line. It does not smell at idle or when filling up.

    The question that comes to mind is could the tank be "weeping" from a small hole at the bottom or sides even though I do not see an visual evidence of fuel in the bilge? If this is the case then I would imagine the next step would be is to replace the tank.

    Any suggestions guys?


  • #2
    From what I understand the fuel tank's are sealed in their own compartment so any gas that leaks out will be confined. This is why you will smell it but not see any in the bilge. It took me quite awhile to realize that one! Mine does it too and I'm going to probably pull the tank out next winter.
    1978 Mako 25 - Blind Hog
    1985 Mako 20c - sold
    Fort Walton Beach, FL


    • #3
      Had the same problem with mine. could never find any fuel in the bilge but strong oder. One day I was working on a new bilge pump and had a drop of gas hit my arm. It was the squeeze bulb dripping but only a drop every minute or so. just enough to give the smell but not enough to leave a puddle.
      1986 Mako 231[br]Kind of ugly now but I love Her![br]New Smyrna, FL


      • #4
        I appreciate the replies. My problem is that it only smells when I get underway. There is no odor when I first start it and sit at idle or when I fill it up. If I had a leak in the tank it would most likely smell at all times since the gas would always be dripping. I'm hoping it's just the line that feeds the engine. I'm going to take a look at it this weekend. I can't see that the tank is totally closed in that it would not have some sort of drainage. Some people say it totally enclosed and others have said that it has some sort of drainage under it.


        • #5

          Some people say it totally enclosed and others have said that it has some sort of drainage under it.

          It depends what year the boat is. The early one's like my '73 do not have the box/coffin for the fuel tank to set on.


          • #6
            My boat is an 84. Any suggestions?


            • #7
              I had this same problem in my 1988 261. What it turned out to be was a pin hole had developed where the vent tube connected to the alum elbow that came from the tank. When the boat was full of fuel the bouncing up and down would cause the fuel to come out of this pin hole. Be sure to check all of your pick up tubes on the top of the tank. I used a small amount of Marine-Tex and that solved my problem.


              • #8
                Thanks Becker. Being that I changed all the hoses my next step was to spray all the fittings with a soapy solution when when I start the motor to see if any leaks shows their ugly face. I'm hoping I find one. For your reference, I just found out that they now make a liquid tank sealant that you pour into gas tanks that will seal any leaks that may be on the bottom of tanks. It was designed for classic cars being that tanks for such cars are hard to come by new. I'm thinking of giving that a shot if I can't find the leak on top. I'll keep you posted.

                Long Island, New York