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Thread: Losing Power at 3,000 rpm's

  1. #1

    Default Losing Power at 3,000 rpm's

    I have a 1985 Bayliner Contessa; it has a Chevy 350 that has a rebuilt carb on it from the carb shop. So, I know the carburetor is in good shape but when I run my boat up on step it falls flat on its face after 3,000 rpm. I put a new fuel filter on it. This past weekend my boat would run at about 15 mph and once in awhile it would bump up to 20mph but when I would give it more gas it would fall flat, or loose power…Any recommendations would be appreciated…

  2. #2

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    have you checked the water fuel seperator, fuel filter they will pulg up if you run your boat low on fuel then refill the tank stears up sediment happed to me once. My boat did the same thing idled fine but when I went to get on step it just won't get there.

  3. #3
    Member Roger45's Avatar
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    Is this a *new* problem? Did it previously run at a higher RPM without problems? The reason I ask is that the 350 engine has many variations on it...if it has the wrong CAM it may not ever idle above 3K. If this is a new problem, then starting with the basics...is it a fuel delivery problem? Compression? Exhaust? What I am saying, we need a little more information before heading you down the right path
    "...and then Jack chopped down the beanstock, adding murder and ecological vandalism to the theft, enticement and vandalism charges already mentioned, but he got away with it and lived happily ever after without so much as a guilty twinge about what he had done. Which proves that you can be excused just about anything if you're a hero, because no one asks the inconvenient questions." Terry Pratchett's The Hogfather

  4. #4

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    This is a new problem, at times it will run over 3,000 rpm to around 3,800 and run at about 28 mph. but most of the time it falls flat...

  5. #5
    Moderator Paul H's Avatar
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    Sounds like it just isn't getting enough fuel. The fuel filter could be clogged, there could be a small air leak that causes the fuel pump to loose prime, or the rebuilt carb might be jetted too lean.

  6. #6
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    Oftentime,fuel lines get aged and lose their sidewall strength and they compress under suction.

    New lines often do wonders.

  7. #7
    Member SusitnaAk's Avatar
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    +1 to all the fuel suggestions, If don,t think that than check the spark advance in the distributor, Make sure that the little plates are free and not rusted or gummed up. hook a timimg light up to it and have somebody watch when bring up to speed that the spark advances with it. Can,t rememeber the spec,s something like 32 Deg.s at higher Rpm You will have to look up at what rpm and what it should be. for the correct amount. Also the points if it has them or the eletric part there, sometimes they will go bad too. Just a thought, something else to look at.

  8. #8

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    Thank you all, I will look at the getting a new fuel line, the boat sat last year because of the fuel prices. I did speak to a machanic that told me to spray WD40 on the inside of my distributor so that all the parts are moving properly. I can't wait to get all the bugs out...

  9. #9
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    I recently had a problem with my 350, where i couldn't get full power. It turned out to be my fuel pump. To listen to it prime and feel it during idle it seemed normal, but in reality it just wasn't delivering enough fuel. I changed pumps and i got my rpms/power back right away.

    Good luck.

  10. #10

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    I had the same problem with a different motor and it was the fuel pump.

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