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Merc 4.3 MPI vs carb

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  • Merc 4.3 MPI vs carb

    Hello. I am in the market for a bowrider, 18 - 20 feet, and I believe I would prefer the merc 4.3. Family use/watersports on local lakes only. I am looking for well maintained excellent condition examples, and it seems that budget will only provide for about a 10 or 12 year old boat.
    My question is: Should I prefer a Merc 4.3MPI, or carb version? In my experience with motorcycles and powersports, I would opt for EFI every time, but I appreciate that this is not a motorcycle. I would have expected that, while hard to find, mpi would be much less likely to be a pia, but many of the problem threads on here have me now questioning that.
    Also, to what degree is the additional power from mpi version likely to be a factor for skiing in a br of 20ft or less?
    Any info appreciated.

  • #2


    Yes, it has been a rough couple of months for those MPI/EFI engines, based on recent threads. MPI engines are great up until the point where they have a problem, then they become a nightmare. Carb'd engines may not be as sophisticated, but when they are having issues, usually you can sort it out fairly quickly with the toolset you got on your birthday..

    I would not be overly concerned about a slight power difference between the two types of engines. If power becomes a concern, then maybe opt for the 5.0 in your search.
    Best regards, Ted . . . . Cape Cod, MA

    Formula 330 Sun Sport, O'Day Mariner Sail #3224, Sunfish
    Past Boats: Catalina 22 Sail #10531, Formula 242 Sun Sport
    Twin Mercruiser 7.4 LX MPI (0F802036, 039), Bravo 3's (0F806198, 199), Mercury 7.5 HP (1969), Johnson 4.5 HP (1980)

    My Boating Web Pages: http://www.tpenfield.com

    Member of the Month - February 2013

    Comment


    • #3
      I would go with a 5.0 or 5.7 myself over the 4.3. Carb is fine vs MPI. as Ted stated, MPI works great until it doesnt. a carb can be diagnosed and fixed with a swiss army knife and a flashlight.
      1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - http://forums.iboats.com/forum/owner...988-rogue-2420

      Past Boats
      1970 Wooster Hellion - Merc 9.8
      2002 SeaRay 190BR - 5.0 - A1G2 - "Cheasheads in Paradise"
      1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

      What’s behind you doesn’t matter.Enzo Ferrari

      Comment


      • #4
        MPI is great while it works, when it acts up, nothing but headaches. Have had a carbed 5.7 VP on an 18 1/2 foot for 15 yrs, wouldn't trade it for a FI for all the tea in china.

        Comment


        • #5
          Agreed on the MPI comments, i think we all agree that mpi is better technology for sure. I think it depends on your mechanical aptitude and how much you enjoy working on the boat. I chose a carb when I repowered because I know I can fix it, but I know that I probably have a carb cleaning and rebuild or two in my future.

          Comment


          • #6
            I like the EFI route. For me it seems easier to work on but I am also an IT guy to is makes sense. The problem may be finding a 4.3l MPI in a boat that fits what you are looking for. I don't see the 4.3l MPI equipment come up for sale to often. You may consider looking for 5.7l EFI. They are a simpler than the MPI but still fuel injected.
            83 Sunrunner 16.5 120 merc Alpha 1 drive SOLD 8/1/13

            1996 Crownline 202BR
            5.7l EFI 0f791070
            Bravo I drive

            GMC Yukon tow rig

            Comment


            • #7
              Originally posted by thumpar View Post
              I like the EFI route. For me it seems easier to work on but I am also an IT guy to is makes sense.
              LOL....so please explain how being in IT makes it easier to work on MPI?
              1998 Wellcraft Eclipse 24 Cuddy
              Volvo Penta Duo-Prop 7.4L "LK"

              2006 Sun Tracker Party Barge 21
              Mercury 90 4-Stroke FI
              "Common sense is not very common"
              "Failing to prepare is preparing to fail." -- John Wooden

              Comment


              • #8
                Originally posted by bruceb58 View Post
                LOL....so please explain how being in IT makes it easier to work on MPI?
                Must be because the engine is run by a computer
                Best regards, Ted . . . . Cape Cod, MA

                Formula 330 Sun Sport, O'Day Mariner Sail #3224, Sunfish
                Past Boats: Catalina 22 Sail #10531, Formula 242 Sun Sport
                Twin Mercruiser 7.4 LX MPI (0F802036, 039), Bravo 3's (0F806198, 199), Mercury 7.5 HP (1969), Johnson 4.5 HP (1980)

                My Boating Web Pages: http://www.tpenfield.com

                Member of the Month - February 2013

                Comment


                • #9
                  It just makes it easier for me to understand then a carb. I get that input signals go in to come up with the way the injectors fire and spark plugs fire to make it run. I also get how carbs work but never good at diaging past rebuild it when it runs bad. I don't know a thing about jetting or setting float other then do what the spec says. To me a computer controlling it is simpler where some a carb is easier.
                  83 Sunrunner 16.5 120 merc Alpha 1 drive SOLD 8/1/13

                  1996 Crownline 202BR
                  5.7l EFI 0f791070
                  Bravo I drive

                  GMC Yukon tow rig

                  Comment


                  • #10
                    Carbs are a hundred times simpler than FI and I came from working with engine control modules when I worked as an electrical engineer for GM!

                    I am guessing you own a Rinda or similar tool when troubleshooting your FI? Same goes for when you troubleshot the FI in your car?
                    1998 Wellcraft Eclipse 24 Cuddy
                    Volvo Penta Duo-Prop 7.4L "LK"

                    2006 Sun Tracker Party Barge 21
                    Mercury 90 4-Stroke FI
                    "Common sense is not very common"
                    "Failing to prepare is preparing to fail." -- John Wooden

                    Comment


                    • #11
                      If you can fix a toilet, you can fix a carb. The theory and operation is the same
                      1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - http://forums.iboats.com/forum/owner...988-rogue-2420

                      Past Boats
                      1970 Wooster Hellion - Merc 9.8
                      2002 SeaRay 190BR - 5.0 - A1G2 - "Cheasheads in Paradise"
                      1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

                      What’s behind you doesn’t matter.Enzo Ferrari

                      Comment


                      • #12
                        Must be the old dogs and new tricks choice for me also . I have a 1999 Four Winns with a 4.3 Carb that I know will always get me home. I also have a 2011 Cobalt 232 that has a 5.7 GSI 300-C that I take the Rinda and two paddles and wing and prayer just to get back to the dock. Dave-R

                        Comment


                        • #13
                          Originally posted by bruceb58 View Post
                          Carbs are a hundred times simpler than FI and I came from working with engine control modules when I worked as an electrical engineer for GM!

                          I am guessing you own a Rinda or similar tool when troubleshooting your FI? Same goes for when you troubleshot the FI in your car?
                          I don't have a Rinda but have eyed them. I do have stuff for cars. There are guys in the Mustang group I am part of taking the FI off their 5.0 engines and switching to carbs. Some of us say they are moving backward and their are others that wouldn't have it any other way.
                          83 Sunrunner 16.5 120 merc Alpha 1 drive SOLD 8/1/13

                          1996 Crownline 202BR
                          5.7l EFI 0f791070
                          Bravo I drive

                          GMC Yukon tow rig

                          Comment


                          • #14
                            it isnt that fuel injection is faulty. it is the cheap-carp parts its made with that fail.

                            plastic has no business anywhere near a motor.

                            i could go on and on about the common failure points of EFI. in a car/truck that gets driven, the car/truck gets replaced/sold/scrapped between the 10-15 year mark when the cheap EFI parts fail because the rest of the car/truck has started to fail.

                            in a boat with minimal hours per year, the parts will start to fail at the 10 year mark, some making it to 15.

                            nothing wrong with EFI or a carb. just understand the design life of the components in the system and replace accordingly
                            1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - http://forums.iboats.com/forum/owner...988-rogue-2420

                            Past Boats
                            1970 Wooster Hellion - Merc 9.8
                            2002 SeaRay 190BR - 5.0 - A1G2 - "Cheasheads in Paradise"
                            1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

                            What’s behind you doesn’t matter.Enzo Ferrari

                            Comment


                            • #15
                              Sign up today
                              Thanks for all the helpful replies. Interesting stuff. I am really starting to lean towards carb, as the boat I buy will likely be 10+ years old.

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