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  1. #1

    Default 350 MAG not revving past 3200 rpm, not planing

    serial: 2A191167
    2014 SeaRay Sundancer 260
    600 hours

    Won't rev past about 3200 rpms. No alarms or any indication of problems on the gauges.

    I caught up on past due maintenance in an attempt to fix the problem: correct plugs NGK 5599, OEM Cap Rotor Wires, Water separating Fuel filter
    Batteries are new, clean tight connections
    no change in performance since completing this work.
    I did find a small chafed leak in the vacuum hose from the fuel pressure regulator (elec taped for now), but I figure that should be a low rpm prob not a high rpm prob.
    prop was bent and has since been replaced, no change
    any help is appreciated!

  2. #2
    Join Date
    Jun 2006
    Location
    Spotswood, NJ, USA
    Posts
    4,844

    Default Re: 350 MAG not revving past 3200 rpm, not planing

    any codes on the scanner report?

  3. #3

    Default Re: 350 MAG not revving past 3200 rpm, not planing

    Quote Originally Posted by Bt Doctur View Post
    any codes on the scanner report?
    I need to do a scan. Iíll need a day or two to report back.
    Im new to boats, but I thought there would be a beep every minute or so if there was an active code. Please correct me if I am wrong.

  4. #4
    Join Date
    Sep 2010
    Location
    Jersey Shore
    Posts
    5,615

    Default Re: 350 MAG not revving past 3200 rpm, not planing

    Is the boat covered in Growth?
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  5. #5

    Default Re: 350 MAG not revving past 3200 rpm, not planing

    Quote Originally Posted by Docksidemarineservices View Post
    Is the boat covered in Growth?
    Yes! Tons. It lives in Lake Michigan- Chicago north end of Belmont Harbor and its a cesspool. Long story short-its a logistical hurdle to get the boat out, but I can do it.

    do i just need a power washer (gas or electric) and a boat trailer?

    (like I said im new to boats, so thank you)

  6. #6
    Join Date
    Sep 2010
    Location
    Jersey Shore
    Posts
    5,615

    Default Re: 350 MAG not revving past 3200 rpm, not planing

    Quote Originally Posted by bortSanders View Post
    Yes! Tons. It lives in Lake Michigan- Chicago north end of Belmont Harbor and its a cesspool. Long story short-its a logistical hurdle to get the boat out, but I can do it.

    do i just need a power washer (gas or electric) and a boat trailer?

    (like I said im new to boats, so thank you)
    Well, I have no experience with bottom growth on lake/fresh water boats.... But here in NJ it is the first thing I look at when I hear this performance complaint especially late in the season.

    A gas power washer and a trailer will give you access to remove almost all of the growth.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  7. #7
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    16,277

    Default Re: 350 MAG not revving past 3200 rpm, not planing

    You'd be surprised how badly marine growth can strangle a boat's performance. I was so pissed at the way my 32 footer was dragging its butt that I cleaned the entire bottom with a 1 1/2 inch wide paint scrapper! Took an hour (and I swallowed a gallon of creek water doing it) but she ran perfectly again.

    Jeff

  8. #8
    Join Date
    Jun 2008
    Location
    Island Heights, NJ,
    Posts
    3,116

    Default Re: 350 MAG not revving past 3200 rpm, not planing

    Here on the Jersey Shore, some of the competitive sailors hire divers to scrub their already bottom painted boat bottoms the day before they race ( usually once a week) . While bottom paint does a decent job of keeping barnacles off of boat bottoms, it does not do so well keeping "slime" from accumulating. Since these sailors are usually in the top three positions seasonally, there must be something to it.
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280

  9. #9

    Default Re: 350 MAG not revving past 3200 rpm, not planing

    thanks to everyone for the replies. I will update when I get it fixed.

  10. #10

    Default Re: 350 MAG not revving past 3200 rpm, not planing

    Well, its not fixed. I didn't do the bottom clean yet. I was able to recreate the problem while it is parked in the slip. When it gets near 3300 rpm it sounds like it is hitting the rev limiter and starts stumbling.

    - I checked for codes: none active. except the "SWITCHED BATTERY VOLTS" code 65 times in the previously active section. I assume thats one of those things you ignore. I might add that this is a rental boat.
    - Fuel pressure at the schrader valve test port between the 2 fuel rails and behind the throttle body: idle = 36-37psi , vac hose of fuel psi regulator removed 46-47 psi. Also the prob occurs with the fuel psi hose removed too. Its a MAC tools fuel gauge and I've really only used it a few times, so it should be accurate.
    -I made a video of the Parameter Data if anyone can help. The fuel trim at the top right of the screen isnt visible, but it's equal to the other banks fuel trim. It also has audio to hear the problem.
    - note: I also have a noise at idle that I dismissed as valve train noise, but I made a video just in case anyone thinks its a bigger issue...(its the second link)

    Any help is very much appreciated. Thanks

    parameter data:
    https://youtu.be/yiyNyncKkYQ


    https://youtu.be/bjYKpE0FUaA
    Last edited by bortSanders; 09-09-2019 at 06:31 PM. Reason: added video of engine noise, formatting

  11. #11
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    7,880

    Default Re: 350 MAG not revving past 3200 rpm, not planing

    Intake Manifold Vacuum looks a bit low at idle and appears to fall off pretty fast....

  12. #12

    Default Re: 350 MAG not revving past 3200 rpm, not planing

    Quote Originally Posted by makomark View Post
    Intake Manifold Vacuum looks a bit low at idle and appears to fall off pretty fast....
    Youre right. I put a vac gauge on and got 14 inHg at idle. I have a misfire on cyl 7.

    Im going to do a compression test.

    thanks

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