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1986 70HP Yamaha Won't Start

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  • 1986 70HP Yamaha Won't Start

    Hello all!
    Earlier this year I acquired a 1986 70HP oil injected Yamaha. I have had it on the water twice and have run it on muffs a couple of times with no issues other than a small leak from the carbs. Thursday I pulled it out to hook it up to the muffs one more time before hunting season. Fires right up, runs for about 5 seconds and dies. Won't start at all. Pull air cover off, and there's a puddle of fuel in the bottom. I assume sticking float. Already had a rebuild kit just in case. I rebuild carb, clean everything up, new fuel, still no go. I've had carb off 3 different times making sure I didn't miss anything. I'm feeling pretty confident it's not a carb issue. I also replaced the plugs with no luck. I did confirm I have good spark.

    If a spray a little fuel mix directly in the air intake, it starts but only runs long enough to burn off the spray, which leads me back to carb, but I don't know what else I could do with it. I've checked all the holes, ports, etc, and they're clean.

    I'm going to pick up a gauge to test compression, but I don't think that's my issue.

    You guys have any other ideas for me? Am I missing anything?

    I went through the previous topics for as long as I could stand, so I hope I didn't miss this previously.

    Thanks for any help you guys can offer!


  • #2
    what happens to the primer bulb when it dies? will it stay running if you pump the bulb? Have you checked any inline fuel filters? does sound like it's starved for fuel. Is there still a leak?


    • #3
      So apparently I had water in the fuel. Dumped the tanks and the carbs again, fresh gas, immediately fired up. Good news is, the carb doesn't leak anymore so I don't believe I wasted my time completely.


      • #4
        Sign up today
        good news, that was a cheap fix. now find out how water got into the fuel.