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  • .338 mag.

    I have two 4 stroke 115 Yamahas on my boat. They have about 350 hours on them. The port motor runs great. The starboard motor acts like it runs out of fuel. Changed the fuel filter a week ago. If I squeeze the ball the motor keeps running. Usually runs for a few minutes and then stops. A couple of times it ran for an hour or so before stopping. Traced the fuel lines and can't find a leak. Found this out on my trip to Whittier the other day. If any of you have any ideas on what could be causing this please reply. Thanks..

  • #2
    Are you running off one tank or two? Sounds like it could be a vent problem if it has it's own tank. Possible water in the tank if your running dual tanks also. Picks water up when it's running do to pitch and motion. Maybe a weak fuel pump although I'm thinking not. Good luck.



    • #3
      my sick motor

      I am running off one tank and one motor runs good. The other motor dies like it runs out of fuel. If I squeeze the ball it keeps running. Can't find a leak in the line.


      • #4
        How about the quick disconnect fuel fitting where it enters the engine cowling. Are your fuel lines long enough to switch them at the engine? If the problem swaps, it's the fuel system, if the problem remains it's the engine.


        • #5
          the sick motor

          I will try to switch lines and hope that is it. Thanks for the help...


          • #6
            Fuel problem...or pump?

            If the motor idles fine but dies when you accelerate, especially after a few seconds, check out your fuel pump. I had an Evinrude that had a tear in the diaphram in the fuel pump that prevented it from keeping up with demand for fuel a few seconds after you gave it some throttle. However, at idle it was able to pump enough to keep it running. Just a thought...
            BK Marine Services 232-6399
            Alaskas only Planar diesel heaters dealer, service, warranty, and installation.
            Alaskas only Lonestar drum winch dealer, Whirlwind props, Stinger gearbox, and Alumatech airboats.


            • #7
              f 115 problems

              Have you checked the connections for the main wiring harness? I had a similar problem with one of my F 100's on my old hewescraft. All symptoms pointed towards fuel delivery. According to Dewey's, the yamaha wiring harnesses were not built long enough to reach from the controls to the power head so they had to spice material in. The connectors they used had corroded. John at Deweys said that dielectric grease should be added every season. Solved the problem.
              sigpicSpending my kids' inheritance with them, one adventure at a time.


              • #8
                This might sound silly, but check the direction of flow on the ball (arrow). I had a primer ball inline backwards once, and it would only run when I pumped it (like you), then it would die when that amout of fuel was burned. It could not pull fuel from the tank, as that ball is a one way check valve. It ate me up till I found it, then I felt stupid that it was so simple and I was digging so deep.

                Good luck...AkBillyBow
                2007 Glacier Bay Cat 2690 Coastal Runner, Twin Honda 150's


                • #9
                  The bulb may be wore out.


                  • #10
                    fuel pump

                    i belive that it is you fuel pump i had the same problem one weekend and ended up squezzing the ball in order to fish. its not that hard to fix. what happened is probably during the winter you either had some water and it froze inside the pump or the diafram craked because it had dryed out. that is my 2 cents


                    • #11
                      Fuel Flow Problem

                      Have you got built in fuel tanks? There's an anti-siphon valve on the tank outlet that can plug giving you the symptoms you describe. Don't just remove it, though, as it is a literal life saver if you ever have a leak in the fuel line that could fill your bilge with gas.


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