Cummins Marine Diesel Repower Specialists › Forums › Cummins Marine Engines › 5.9 BTA low power issue

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  • September 18, 2023 at 10:29 pm #154596

    elliott womack
    Participant
    Country: United States

    I am trying to diagnose a low power issue. Its a 30 foot fishing boat with twin 5.9 bta’s. It was running perfectly after a rebuild or if anything port engine was little stronger after being rebuilt. But now its cant get over 2400 RPM at WOT. There is no smoke of any kind coming out the exhaust. Trying to figure it out I have taken some data readings with pressure gauges and hand held tach. Confirmed throttle lever is moving all the way to its stop. Removed fuel shut off solenoid and confirmed lever is pulled all the way.(starboard engine is running perfectly).

    At the dock in neutralĀ 

    WOT is over 3000 RPM

    Fuel pressure on gauge at secondary filter outlet is almost 30psi

     

    Underway full load WOT:

    2400rpm

    Fuel pressure on gauge at secondary filter outlet is almost 30psi

    No vacuum to speak of on racor vacuum gauge

    No exhaust smokeĀ  Ā 

    What should I check next?

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Viewing 6 replies - 1 through 6 (of 6 total)
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  • September 25, 2023 at 1:50 pm #154840

    elliott womack
    Participant
    Country: United States

    No, no synchronizer installed on the boat

    September 25, 2023 at 6:11 am #154789

    Rob Schepis
    Forum Moderator
    Vessel Name: Tenacious
    Engines: 6BTA 5.9 330's - "Seaboard Style"
    Location: Long Island, NY
    Country: USA

    Are you running with a synchronizer engaged ?

    September 24, 2023 at 9:22 pm #154779

    elliott womack
    Participant
    Country: United States

    (Port) 46047939Ā  <-(engine with low power issue)

    (Stbd) 46041775

    The boat used to run about 28 29 knots at WOT at 2900rpm. Currently the port engine cant get over 2400rpm and that is with the starboard engine pulling most of the load new WOT speed about 24 knots.

    September 23, 2023 at 1:05 pm #154752

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    two things for sure as we have to guess..

     

    engine serial number’s??

     

    Exactly what does running perfectly mean vs. now can’t get over 2400RPM

     

    Way too much is missing here if you want some logical help

     

     

    September 23, 2023 at 6:43 am #154741

    Francis Valerio
    Participant
    Vessel Name: overslept
    Engines: Twin 4BT CPL741
    Location: Massapequa Park, New York Long Island
    Country: USA

    What CPL and what HP?

    6BTA engines can have Cav pumps, Nippon Denso pumps and Bosch 7100 pumps

    They are all very different and someone may have insight specifically on your particular engine

    September 22, 2023 at 11:03 pm #154740

    elliott womack
    Participant
    Country: United States

    Hauled the boat out today to clean the bottom and inspect the propeller. No issues there. Still only getting 2400rpm

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