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Changing Fuel Fill & Vent Hose

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  • Changing Fuel Fill & Vent Hose

    I have a '74 Mako 20' CC. I would like to change out my fuel fill & vent hose, I have already changed out the hose from the tank to the motor. I really don't want to remove the console, is there a way to get to those fittings that are under the center console without removing it

    Thanks in advance for any help

  • #2 have an ordeal on your hands. The fill and vent lines are fully foamed in the gunnels. Mako used pieces of aluminum pipe to go thru the stringers and they usually corroded out first. Removing the fill line usually involves cutting some access holes to dig out foam and break the hose free. I gave up on mine 25 years ago and put a fuel fill line up thru the console.
    Chris Miller[br]Mystic Islands, NJ[br]1974 17 Classic[br]1988 211 Classic (sold)[br]1990 Grady White 230 Gulfstream (sold)[br][img][br]


    • #3
      The fill isn't really my problem but the vent is, I would like to change it out, is the vent connection under the deck or can it be reached from inside the console, I won't be able to get to my boat til Monday

      The problem is ill be running fine then the ball will collapse & I stall out I blew it out with compressed air but it happened again, I was making plans to do a tank replacement this fall when a friend suggested that I change out the vent hose to see if that would fix the problem, so I figure it would be a lot cheaper & easier to try that first

      I was hoping I could get blue prints from this site, I thought I saw them on here before, I'm sure there has been either something similar to my problem or a 74 tank replacement that I could view, I've had the boat for about 10 years & would like to get it back to running great,

      Thanks in advance for any ideas that anyone comes up with


      • #4
        If I could get to the vent connection I could run a separate vent through the console & save myself the headache of snaking it through the deck

        Again thanks in advance for any ideas


        • #5
          I learned a lot about fuel systems, the hard way.

          The vent is on the side of the boat. If you pull the fill cap off and can blow freely through the vent and get air coming out the fill, a collapsed/plugged vent isn't likely. Another check is to run it with the fuel fill loose (watch the water spray!) to rule out a vent issue.

          Most tanks have an anti-siphon fitting at the fuel hose connection at the tank. This is to prevent filling the bilge with fuel if a fuel leak occurs in the fuel line between the tank and the engine. I would highly recommend starting there; it's a $12 part and a lot easier than replacing the vent line. It is the barbed fitting on the tank that the fuel hose to the engine connects to. You can remove it and try to blow through it, if the ball is stuck it will restrict fuel flow to your engine just as you describe.


          • #6
            Thanks for the reply

            There is no anti siphon valve I had that checked last year also I had compressed air pumped in through the fuel fill & it blew out a leaf through the vent & I thought that fixed the problem, however the problem continued, a friend suggested changing the vent hose because he thinks that the hose could be deteriorating on the inside causing a possible flap closing the hose from the movement of the boat, like I said I was going to change out the tank & hoses until I figured I'd have nothing to lose if I changed the vent hose out first

            Please if there are other opinions on something to try , I really appreciate the Input


            • #7
              When I pulled my aluminum vent out, it was completely blocked with jelly like corrosion. I'd never seen anything like it. The vent fitting itself was so corroded that I couldn't get the backing nut off the vent to remove it. I ended up having to cut around it, patch the vent hole, and redrill for a new vent.


              • #8
                On my 1975 20' there is a small access hatch under the console on the coffin cover. My fill and vent connections could be accessed from it. It would have been a real difficult job to do through that small hole.

                Look at my rebuild thread to get an idea of what my vent line looked like. It was a few feet of straight aluminum tubing connected to the tank, with rubber hose turning up the gunwale to the vent port on the side of the hull.

                The challenge will be to get the aluminum tube loose from the tank, and to get enough grip on it to pull it out. On mine it only took a couple of twists to free the small dia tubing from the foam it was stuck to. Of course I had the console off, the coffin lid off, and the tank out. You'll also have to pull the new line in attached to the old, or at least a pull cord to get the new line back in. You may need to check the loop in the rubber section to make sure they didn't use a hose clamp to create the loop.

                Good luck.
                “On the days where I keep my gratitude higher than my expectations, I have really good days.”

                M20 project-Finally Splashed!


                • #9
                  I did not know that they used metal tubing, I thought it was just that black hose , when I changed out the hose that went from the tank to the motor, I connected the new hose to the old hose & pulled it through, no problem, I thought it would be the same process if I could get to the connection. I'll check it out this week, but I guess if I can't get to the connection its back to the original plan & change out the tank

                  Thanks again for all the replies