Announcement

Collapse
No announcement yet.

brand new mercruiser 383 stroker loses power at 3500 rpm(39)s-gctid815078

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    brand new mercruiser 383 stroker loses power at 3500 rpm(39)s-gctid815078

    Hi gang this is my first post but would like to say thank you to this community that has been a huge resource thus far.

    I recently installed a new 383 stroker and have about 8 hours on it so far. initially i was able to obtain around 2500 rpm's and cruise at 8-10 knots. Anything higher and the engine would putter out but not stall. I could back it down to an idle and then power up again and get the same result.

    I have checked the fuel water separator by dumping it into a mason jar and it was clean. I then checked and replaced the in line fuel filter provided by mercruiser with the engine and found no restrictions. I then went further back to the fuel pick up and found the anti siphon was hard to blow air through. I pulled the pick up tube to check the screen and there was not one on it. I replaced the anti siphon fitting with a regular brass barbed fitting for testing purposes and now can obtain around 3500 rpm's before having the same issue as before. As stated this is a brand new crate engine from mercruiser and I have a bravo 3 out-drive on a 1989 bayliner cierra 2858 command bridge.

    On to my question, is the 3/8 fuel line large enough to supply the engine with adequate fuel or should i upgrade to a 1/2 inch line?

    Any help or opinions is greatly appreciated

    Thanks

    Ron

    #2
    Have you checked fuel pressure at the carb or after the pump you pump might be weak.

    If pump is good blow back thru all lines back to tank make sure no blockage.

    Did you replace or change anything in the fuel delivery into your motor? Carb or anything else?

    3/8" lD fuel line is plentiful for a small block.

    3/8" ID will accommodate most big blocks..
    Bayliner 2252 5.7l alpha one gen 2

    Comment


      #3
      Forgot to mention in my first post, this is the multi port fuel injected version of the strokers. Have not put a fuel pressure gauge on it at this point but i can give that a try.

      Comment


        #4
        Temp is good ?

        Maybe the valves are too tight ?

        All the plugs are firing ?

        Tell me you preformed a compression test ? Wrote the numbers down for future reference .
        Be good, be happy, for tomorrow is promised to no man !

        1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

        '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

        Manalapan N.J

        Comment


          #5
          "ron12512" post=815078 wrote:
          Hi gang this is my first post but would like to say thank you to this community that has been a huge resource thus far.

          I recently installed a new 383 stroker and have about 8 hours on it so far. initially i was able to obtain around 2500 rpm's and cruise at 8-10 knots. Anything higher and the engine would putter out but not stall. I could back it down to an idle and then power up again and get the same result.

          [color]blue wrote:
          I would strongly suggest that you steer clear of the 2.5k rpm range (and the 10 knots) for any duration.

          At 2.5K rpm/10 knots, your hull is pushing quite a bit of water being that it is not up on steep.

          This puts your fresh engine right at the cusp of a Detonation Prone RPM!

          I would avoid this until you sort things out. [/color]

          I have checked the fuel water separator by dumping it into a mason jar and it was clean. I then checked and replaced the in line fuel filter provided by mercruiser with the engine and found no restrictions. I then went further back to the fuel pick up and found the anti siphon was hard to blow air through. I pulled the pick up tube to check the screen and there was not one on it. I replaced the anti siphon fitting with a regular brass barbed fitting for testing purposes and now can obtain around 3500 rpm's before having the same issue as before.

          [color]blue wrote:
          As for the Anti-Siphon valve..... any marine fuel pump should be able to pull fuel through this valve!

          Also, remember that this is a USCG requirement.[/color]

          As stated this is a brand new crate engine from mercruiser and I have a bravo 3 out-drive on a 1989 bayliner cierra 2858 command bridge.

          On to my question, is the 3/8 fuel line large enough to supply the engine with adequate fuel or should i upgrade to a 1/2 inch line?

          [color]blue wrote:
          Whether MPI, TBI or Carbureted, the 3/8" fuel line will supply plenty of fuel for a SBC engine.[/color]

          Any help or opinions is greatly appreciated

          Thanks

          Ron
          [color]blue wrote:
          Ron, FYI and FWIW........ the 383 cu in SBC (aka 6.3L SBC) is not a new engine. It is a re-manufactured engine (4.030" bore).

          The 377 cu in SBC (aka 6.2L SBC) is a new engine (4.000" bore).

          None-the-less, if this is an MPI engine, it will require Merc's control system and the correct MPI fuel pump.

          Did you follow Merc's directions when installing and connecting up your wiring and fuel system?

          Are you using a full size Marine Fuel Filter? (not the little automotive style)

          [/color]

          Maybe the valves are too tight ?
          [color]blue wrote:
          There is no adjustment of valves.

          There is an adjustment to the cam follower plunger depth, of which if wrong, could prevent a valve from fully seating. However, this should have been adjusted by Merc.

          Also, if this was out of spec (after 8 hours run time), you would have noticed the symptoms and/or the damage by now. [/color]
          Rick E. Gresham, Oregon
          2850 Bounty Sedan Flybridge model
          Twin 280 HP 5.7's w/ Closed Cooling
          Volvo Penta DuoProp Drives
          Kohler 4 CZ Gen Set

          Comment


            #6
            He removes the anti siphon and gets more rpm, makes me think fuel delivery issue. Maybe a test run with the fuel fill cap removed to eliminate a tank vent issue. Is there gunk in the fuel tank that plugging up your filters prematurely ? I agree that the fuel pump should be tested. You also say there is an inline fuel filter somewhere. Could this be causing a fuel flow restriction? How big is that filter? Have both filters (main and inline) been replaced?
            Dave
            Edmonds, WA
            "THE FIX"
            '93 2556
            Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

            The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
            Misc. projects thread
            https://www.baylinerownersclub.org/f...56-gctid789773

            Comment


              #7
              What year and drive ?
              Be good, be happy, for tomorrow is promised to no man !

              1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

              '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

              Manalapan N.J

              Comment


                #8
                "Chief Alen" post=815302 wrote:
                What year and drive ?
                See post #1!

                .
                Rick E. Gresham, Oregon
                2850 Bounty Sedan Flybridge model
                Twin 280 HP 5.7's w/ Closed Cooling
                Volvo Penta DuoProp Drives
                Kohler 4 CZ Gen Set

                Comment


                  #9
                  Check the fuel pressure at the rail,

                  Check to see which cool fuel module is equipped with...
                  Joon, Kathy, Jaden & Tristan
                  Uniflite 42 AC, DD 671N
                  93 3058 sold
                  92 2855 (day boat)
                  91 Fourwinns 205 (lake boat)
                  Longbranch WA
                  Life is Good

                  Comment


                    #10
                    Missed it. oh well.
                    Be good, be happy, for tomorrow is promised to no man !

                    1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

                    '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

                    Manalapan N.J

                    Comment

                    Working...
                    X