• If this is your first visit to the iboats.com Boating Forums, be sure to check out the FAQ. To post a question or comment, begin by signing up. To start viewing messages, select the forum that you want to visit from the selection below.


Announcement

Announcement Module
Collapse

Help Tip: If you have a question that has not been answered to your satisfaction in the archives, it is always best to start a new thread of your own. By starting your own thread, you will receive the maximum number of views by forum members.

Below are some additional forum policies in hopes of all iboats members will follow, Thank you.

1. Please do not reply to old topics or hijack existing topics. Old topics of a technical nature are like a library book, Please do not write in them.

2. Old topics should be considered archives and used for reference only. Please do not reply to them.

3. Do not take over someone elses topic (aka hijack) with your own question, even if it is similar. If you have a question that has not been covered to your satisfaction in the archives, it is always best to start a new topic of your own.

4. If you have a question for the original poster (OP) and the topic is over 30 days old, send the OP a PM, he may not even visit the forums any longer, or may not notice your question in the old topic.

5. By starting your own topic, you will receive the maximum number of views by forum helpers that may not even notice your question when its posted at the end of someone elses topic. And those answers will be specific to your particular issue.

6. Please do not post to topics that have been inactive for more than 3 months unless you are the original poster. We have very active forums and any topic that remains inactive for that long should be considered "dead". It is especially confusing when there is an entirely new question posted to an old topic.

7. Posting at the end of any topic is considered to be hijacking the original posters topic which in turn subjects the topic to be closed if it continues to happen thus not making it fair to the original poster in the future had for some reason he/she needed to return for additional information or provide an update of the problem solved which is always welcomed within a reasonable amount of time frame.

8. Please note that you should see a red banner pop up near the bottom of each inactive topic asking you not to reply to old topics. The Red banner will read: Please note this topic has been inactive for 90 days. For the best results, please start a new topic.

Thank you all in advance for doing your part in helping iboats run a smooth ship.

Additional forum rules linked below.
http://forums.iboats.com/forum-rules-guidelines-405/
See more
See less

mercruiser 4.3 engine won't stop

Page Title Module
Move Remove Collapse
X
Conversation Detail Module
Collapse
  • Filter
  • Time
  • Show
Clear All
new posts


  • mercruiser 4.3 engine won't stop

    I have a 2005 Mercruiser 4.3 190 hp in a Bayliner 185. After running for an hour or more the engine will run on after the key is turned off. Sometimes just a few seconds but often for 15 seconds or more? Dealer suggested turning engine off while still in gear but this doesn't seem to help much. Someone else suggested ignition timing may be off but it seems to run well except for getting the engine to stop. The engine has only about 20 hours. Thanks for any advice.


  • #2
    Re: mercruiser 4.3 engine won't stop

    Get it back to the Dealer,+ Get it Fixed,.....

    It'll Cost you a new Motor if you Don't........

    Mercruiser has issued Service Bulletins about it......
    Any Grease is Better,..... Than No Grease at All.......

    Comment



    • #3
      Re: mercruiser 4.3 engine won't stop

      Yep, timing or idle too high.

      Comment



      • #4
        Re: mercruiser 4.3 engine won't stop

        Originally posted by imported_Coors View Post
        Yep, timing or idle too high.
        Carbon buildup is more likely.

        Comment



        • #5
          Re: mercruiser 4.3 engine won't stop

          Yep, that could do it too.

          Comment



          • #6
            Re: mercruiser 4.3 engine won't stop

            Has it done this since it was new?
            My volvo 4.3 did it from the start. I lowered the idle speed to 600-700 RPM,( idle speed was too fast around 850 rpm)
            and switched to 89 octane fuel. Also I always try to let the engine idle for a few seconds before shutting down. It seems to have stopped the problem.

            Comment



            • #7
              Re: mercruiser 4.3 engine won't stop

              There are bullitins about this.Change gas,plugs,timing,add a carb kit, ....

              First thing I ask my customers to do is tool around the pond a bit before turning the key off,or let her idle for 2 minutes at least.Get the temp down.
              Unfortunately todays gas is made for cars,not boats.

              If your dealer is not aware of this ....... your choice

              DHP

              Comment



              • #8
                Re: mercruiser 4.3 engine won't stop

                Here is a copy and paste of the Mercruiser service bulletin no. 97-17

                = Revised July 1999
                Engine ‘Dieseling’ or ‘Running-On’
                Models
                MCM 4 Cylinder, V6 and V8 with Carburetors.
                Situation

                Under certain conditions, carbureted engines may ‘run-on’ when the ignition key is turned off. Normally, it
                will take a combination of several of the following conditions to make the engine ‘run on’. These conditions
                include but are not limited to:
                1. Type and formulation of gasoline available in the area.
                2. Type of boat and its engine compartment ventilation system.
                3. Outside air, inside engine compartment air and engine coolant temperatures.
                4. How quickly the engine is shut off after running at cruising or higher RPMs.
                5. How the boat and engine are operated.
                6. Engine idle rpm set too high.
                7. Wrong heat range spark plugs or spark plugs with deposits on them.
                8. Deposits in combustion chamber.
                Carbureted engines, unlike EFI, do not shut off the fuel supply to the engine when the ignition key is turned
                off. As the engine is coasting to a stop, air is still flowing through the carburetor into the manifold. This air
                flow can still draw fuel from the carburetor, through the intake manifold and into the combustion chamber.
                A hot spot in the combustion chamber will cause this fuel/air mixture to burn. The engine now ‘diesels’ or
                ‘runs on’ although the ignition system is not firing. EFI engines do not have this problem because the injectors
                do not inject fuel once the ignition key is turned off.
                Suggestion to Minimize ‘Run On’
                Items number 1 ,2 and 3 can correct or reduce most of these ‘run on’ problems. Letting any engine idle a
                minute or two before shutting it off is desirable. This helps the engine to normalize at idle rpm before being
                shut down.
                1. Be sure engine idle mixture, idle rpm and ignition timing are correct. On 4 cylinder and V6 or V8 engines
                with Thunderbolt IV ignition, setting idle rpm as low as possible can help stop ‘run on’.
                2. Adjust throttle cable barrel so that the carburetor’s throttle lever returns against the idle speed stop
                screw every time the remote control throttle lever is returned to neutral, idle.
                3. Idle engine 1 to 1-1/2 minutes before turning key off after running at cruise or higher engine rpm.
                4. Try a different brand of regular fuel or try some premium fuel.
                5. Increase idle mixture by 1/8 turn ‘richer’.
                6. Go to next colder heat range spark plugs.
                7. V6 and V8 only: Install a 140 F(60 C) thermostat
                Don S.

                sigpic

                Please, no PM's (Private Messages) regarding boat/engine problems.
                That is what the forums are for.
                Only forum/moderator issues will be answered in PM's.

                Comment



                • #9
                  Re: mercruiser 4.3 engine won't stop

                  The boat was purchased new last year. It started doing it last year after being on the water for a few times. Yesterday was first time out this year and it was pretty bad. Idleing before stopping may help, but we're skiers and it's a little impractical when skiers are down. Thanks to everyone for your help.

                  Comment



                  • #10
                    Re: mercruiser 4.3 engine won't stop

                    Aren't you basically at idle picking up the skier?

                    Comment



                    • #11
                      Re: mercruiser 4.3 engine won't stop

                      Engine should be off when skiers are getting on board. We're in the river and trying to get them picked up as quickly as possible when down.

                      Comment



                      • #12
                        Re: mercruiser 4.3 engine won't stop

                        Over the past 2-3 yrs, my '97 4.3 Liter Mercruiser has had the same issue of wanting to still run after ignition turned off.

                        For the 2nd time now, the motor has locked up - wont' turn over. 1st time, I stripped flywheel trying to start it. Local mechanic found water in the cylinder heads but no source of water leak - no cracks in blocks. Compression tests showed 150 on all cylinders but 140 on #3.

                        Just this weekend, it locked again. I took out the spark plugs & blew water out the cylinder heads.

                        The motor ran fine for the first 10 years I had it. The past 2 years, it has had the problem of continuing to want to run after shutting off key. More severe, both times that the motor has locked up.

                        Any suggestions on the source or any good mechanics in the St. Paul/Minneapolis, MN area?

                        Thanks,
                        Mark

                        Comment



                        • #13
                          Re: mercruiser 4.3 engine won't stop

                          Smitty, you need to start a new thread.

                          Comment



                          • #14
                            Re: mercruiser 4.3 engine won't stop

                            Originally posted by rbrandel View Post
                            Engine should be off when skiers are getting on board. We're in the river and trying to get them picked up as quickly as possible when down.
                            This is something I have never understood about skiing... Why does the engine need to be shutdown when picking up a person in the water? If it's to ensure the prop isn't turning, then that's why you have a shift control... It may be a hangover from the old days when ski boats had big old V8s in them that were bolted to a propshaft, without a gearbox. I can well understand it in that situation, but the modern sterndrive does have a gearbox, use it....

                            I work in the offshore industry and we are all well versed (too well versed sometimes) in emergency procedures, that includes recovering people fro the water... The first rule is NEVER shutdown an engine, especially in crowded waters, when picking up people. You need that engine running and ready to go....

                            If you have just been pulling a skier around your engine has been under maximum load and the cylinder temperatures will be sky high.... THAT is the main reason it's running on... Let it idle and get the cylinder temps down....

                            Chris.............
                            The world takes on a whole new perspective when viewed from 100' below...



                            1972 Bertram 'Bahia Mar' 20
                            2006 Mercruiser 4.3MPI (0W617679) w/Alpha 1 Gen II (0W829301)
                            **
                            Please don't send service questions in private messages. That's what the forum is for. Messages of thanks, always accepted.
                            **
                            Member of the month - April 2013. http://www.iboats.com/blog/achris-member-of-the-month/

                            Comment



                            • #15
                              Re: mercruiser 4.3 engine won't stop

                              Originally posted by smittys5 View Post
                              Over the past 2-3 yrs, my '97 4.3 Liter Mercruiser has had the same issue of wanting to still run after ignition turned off.

                              For the 2nd time now, the motor has locked up - wont' turn over. 1st time, I stripped flywheel trying to start it. Local mechanic found water in the cylinder heads but no source of water leak - no cracks in blocks. Compression tests showed 150 on all cylinders but 140 on #3.

                              Just this weekend, it locked again. I took out the spark plugs & blew water out the cylinder heads.

                              The motor ran fine for the first 10 years I had it. The past 2 years, it has had the problem of continuing to want to run after shutting off key. More severe, both times that the motor has locked up.

                              Any suggestions on the source or any good mechanics in the St. Paul/Minneapolis, MN area?

                              Thanks,
                              Mark
                              A. Start a new thread
                              B. I bet the manifolds and elbows are original, yes?

                              Chris...........
                              The world takes on a whole new perspective when viewed from 100' below...



                              1972 Bertram 'Bahia Mar' 20
                              2006 Mercruiser 4.3MPI (0W617679) w/Alpha 1 Gen II (0W829301)
                              **
                              Please don't send service questions in private messages. That's what the forum is for. Messages of thanks, always accepted.
                              **
                              Member of the month - April 2013. http://www.iboats.com/blog/achris-member-of-the-month/

                              Comment

                              Working...
                              X