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2006 Stingray 250LR with 5.7 Volvo Penta Acceleration/Power

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  • 2006 Stingray 250LR with 5.7 Volvo Penta Acceleration/Power

    I have a 2006 Stingray 250LR with a 5.7 Volvo GI-F (specific numbers below) and recently just had the motor pulled and a decent amount of work done to it. Had oil leak so oil pan replaced, starter replaced, new motor mounts, new valve covers, manifolds/risers, fuel pump, and props refinished. Ever since the service the belt is squeaking (not replaced) and the acceleration is awful. at idle, the boat is the same, top speed is mostly the same (hesitates a little at WOT), but when we hit the gas to get up and go from no wake zone, the boat just sounds very throaty and takes forever to get on plane. We use the boat almost on a weekly basis so it runs through plenty of fresh gas that we get at our marina. We are in Florida so the boat is used year round. Any ideas? I did buy a new belt to hopefully stop the squeaking but haven't installed it yet (the old one does not seem loose). The mechanic that did all the work did say he adjusted some of the valves too. but the boat back in 2006 when we bought it used to go 45-50mph and now struggles to go 30, is it normal for a boat to lose that much power over time? Any help is greatly appreciated!

    Engine 5.7 GI-F - 3869311 - 4012171401
    Transom Assembly 3869341 - 4151108010
    Drive Unit - DP-SM 1.95(M22) - 3868913 - 4202157526

  • #2
    It would be worthwhile to do a compression check to assess base engine wear, etc.

    I would also look at engine timing, a retarded spark throws a bunch of "heat" out the exhaust which could potentially be used for pushing down on the piston. I cannot say how that's done on your engine.

    Your fuel pressure and knock sensing would be other factors which could directly affect power.

    Adjusting valves is also an interesting proposition. My viewpoint is that valves themselves are not adjusted. Its the ball pivot nut on the center post of the rocker arm which is adjusted to compress the pushrod into the hydraulic lifter in a system with stamped-steel rocker arms. If a rocker arm was over-tightened (meaning over-adjusted downward) there is a possibility that this valve never fully closes/never touches the seat when the hydraulic lifter is on the base circle of the cam. Personally I would never touch the valvetrain unless I had a visible problem or a ticking/knocking sound in a single cylinder hinting at lost motion in the entire valvetraim (cam-pushrod-rockerarm-valve tip) where the hydraulic lifter didn't have enough internal travel to remove the lost motion. So maybe its worth going thru this. It involves removing the rocker covers, turning the engine over by hand slowly to various positions where the lifter is on the base circle and not the nose of the cam, loosening on the ball-pivot until lost motion is detected, and then adjusting down a certain number of turns which is where it stays. No need for further adjustment unless there's a tick which is most often found at idle. Its been a few years since I worked on a pushrod valvetrain so the specifics are lost but that's the basic procedure.

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    • #3
      Thanks for the information, I am trying not to completely pull apart the motor again. Hoping that the mechanic that worked on it recently will have some insight on what he did or didnt do... just spent over $6,000 on this motor and the boat is still not running right... i dont want to just keep throwing money at this boat and not sure i can even sell it with the way its running. very frustrating, I am having an extremely difficult time finding anyone to even work on it (everyone in FL apparently only works on outboards).

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      • #4
        So Update... I went down to the boat today to put a new belt and raw water impeller. While I was there, I wanted to test the fuel pressure at the fuel pump and fuel rail... The schrader valve on the pump was smaller than the two adapters I had so I couldn't check that one (low pressure I believe) but I did check the pressure up on the fuel rail through the schrader valve there and with just the key on, it was right at 50 psi (steady) which i believe is ok but once i started the motor, it jumped to around 90psi with the needle shaking between 90-95... anyone know if that would seem like a bad high pressure fuel pump or a bad pressure gauge? my old fuel cell is trash but i have the old OEM fuel pumps off of it (cheap amazon fuel cell on there now). I think i am going to put the old Volvo pumps on the new housing and see what I get with that... any direction would be helpful! thanks!

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        • #5
          Originally posted by mtymax View Post
          Ever since the service... and the acceleration is awful. at idle, the boat is the same, top speed is mostly the same (hesitates a little at WOT)," "but the boat back in 2006 when we bought it used to go 45-50mph and now struggles to go 30, is it normal for a boat to lose that much power over time?
          At first you say the Top speed is about the same, then later you say it has dropped from "45 - 50 mph" to "struggles to go 30". ????

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          • #6
            fuel pressure too high.
            Suggest you ask your Volvo dealer about parts bulletin P-23-7
            Sounds like you might need Clip # 21491831
            Good Luck Muc

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            • #7
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              Couple of things are confusing me. The top speed isn’t affected but also used to do 50 and only does 30 now ?
              what fuel rail are you testing at ? Is this not a tbi engine ?
              regardless. The throaty noise you mention usually means a lack of fuel or bad fuel.

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