What would cause my 320 fiesta vee to struggle getting on plane

dljboatsdljboats Member Posts: 2 ✭
in Engine Discussions
We purchased this summer a 2005 320 fiesta vee with twin 5.0 mercruiser engines. Ran great the first month. Then one day couldn't get over 25mph, and the following day could not get over 13mph. Could not get on plane at all.our mechanic did a complete tune up on both engines and did find a fuel line leak. He replaced the fuel line. Took boat back out and still no change. could not get on plane at all.he has now blown out the fuel lines and did find some gas in them . Took boat back out today on a flat lake, was able to get on plane but it was a struggle. Never got over 24 mph... any ideas
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Answers

  • LaReaLaRea Member, Moderator Posts: 8,074 mod
    Welcome to the forum.  Is the hull clean?  Bottom growth will kill performance.  Depending on where you are, you might need to have the bottom cleaned halfway through the season.  
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  • Liberty44140Liberty44140 Member Posts: 4,414 ✭✭✭✭✭
    And did he do fuel filters in that tune up or just plugs, wires, cap and rotor?
    07' Cruisers 390 (Previous Rinker's: 06' 342EC & 01' 310FV)

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  • dljboatsdljboats Member Posts: 2 ✭
    2 people were on board. We had boat lifted yesterday and it was clean. We had it  bottom painted after we purchased it, that was beginning of July. Yes fuel filters were  replaced  in tune up.
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  • LaReaLaRea Member, Moderator Posts: 8,074 mod
    Fuel, air, spark.  Do the engines backfire when you hit the throttle?  That could indicate water in the fuel.  

    Are you getting any unusual beep alarms when you start the engines?  Beyond that, I'm running out of suggestions.

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  • johnrenwickjohnrenwick Member Posts: 3 ✭
    You might have something stuck on the outdrive. I had the same problem and a passenger suggested a hard reverse. I came to a stop, put the throttle in reverse and gave her the gas for a short time. Before I swamped, I stopped and resumed my forward course. All was fixed. Must have been something I picked up in the river.
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  • zaverin1zaverin1 Member Posts: 1,672 ✭✭✭
    Compression check?
    both engines able to hit rpm ?
    how old is the fuel
    or recent fill
    up.
    gas tank air vents checked?
    if props are clean, couplers are good and compression is good start looking at ignition and fuel 
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  • zaverin1zaverin1 Member Posts: 1,672 ✭✭✭
    Oh and make sure drives trim proper up and down 
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  • dalekdalek Member Posts: 260 ✭✭✭
    Next time you are out, try accelerating a little with one engine only, and then the other, to see if they respond similarly. If you have one good engine and one weak engine, it is not always obviously apparent.
     As you are moving and water flows over the propeller of the weak engine it may effectively partially assist in powering this motor and the engine RPM may match the good engine, even though the weak engine is totally gutless.
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  • rasburyrasbury Member Posts: 8,971 ✭✭✭✭✭
    Diesels?
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  • zaverin1zaverin1 Member Posts: 1,672 ✭✭✭
    No propane 
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  • reneechris14reneechris14 Member Posts: 3,134 ✭✭✭✭✭
    ??injectors?? Does a motor pop(small back fire) when giving to much throttle. 
    2005 Rinker FV342  Pawcatuck river,Ct
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  • scotteboy1scotteboy1 Member Posts: 1 ✭
    Has anyone heard of a load limiting sensor? Supposed to be a safety feature that won’t allow your boat to exceed certain rpm’s but will allow you to move slowly.
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  • Handymans342Handymans342 Member Posts: 10,375 ✭✭✭✭✭
    Yes we have
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  • Black_DiamondBlack_Diamond Member Posts: 5,439 ✭✭✭✭✭
    Your mechanic should be able to read the engine code faults and if it is going into guardian mode.

    Past owner of a 2003 342FV
    PC BYC, Holland, MI
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  • LaReaLaRea Member, Moderator Posts: 8,074 mod
    edited March 2018
    @scotteboy1 -- "Load limiting sensor" is a general term.  In modern engines, the engine computer uses all available sensors (oil pressure and temp, coolant temp, etc.) to find potential problems.  If something is wrong, the computer will reduce power to avoid damage.  (Also known as "guardian mode")
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