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Cant get mercruiser 4.3 in time!!!!!!!

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  • Cant get mercruiser 4.3 in time!!!!!!!

    I have a 1995 maxum with a mercruiser 4.3 vortec webber 4 barrel carb thunderbolt IV ignition system. Recently I had an issue with it not starting. So I replaced the dist cap rotor wires plugs rebuilt the carb new fuel pump and fuel lines, I checked the tank vent and check valve. im getting plenty of fuel. I got it running after finding out My oil pressure switch was bad. Now I can not get the motor to run on 8 deg before tdc. It will run at about 25 deg btdc but nothing close to what it is supposed to be. under load at this timing obviously the motor runs like crap hesitating stalling and just running like crap. What could be causing this??? I am at wits end trying to figure out what is going on. I have verified that the plug wires are in the right order. Please help.


  • #2
    Re: Cant get mercruiser 4.3 in time!!!!!!!

    are you checking timing on #1 cylinder??

    did you remove the distributor at all??

    do you need to put the ignition into service mode to check/set timing and idle??
    Sometimes when people try to save a penny, they end up spending a dollar

    It is best to fully understand how to properly operate, inspect, troubleshoot and repair your equipment

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    • #3
      Re: Cant get mercruiser 4.3 in time!!!!!!!

      I have verified that when tdc the rotor is pointing to number one. I have not removed the dist. and on thunderbolt IV there is no timing mode like thunderbolt V has.

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      • #4
        Re: Cant get mercruiser 4.3 in time!!!!!!!

        the rotor is pointing to number one.
        does that mean pointing to #1 cylinder or #1 on the cap?
        http://www.boatfix.com/merc/Servmanl/18/18B4R2.PDF
        NO PERSONAL QUESTIONS, THIS IS WHAT THE FORUM IS FOR.

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        • #5
          Re: Cant get mercruiser 4.3 in time!!!!!!!

          Make sure you are on cylinder #1

          Here is the manual you need.

          http://www.4shared.com/document/IqpH...anual_7_GM.htm
          sigpic

          1969 StarCraft Chieftain, 4.3 Mercruiser Alpha One Gen II

          Link To Restoration Page


          ----------------------------------------------------

          Its What I Don't Say You Should Be Worried About...

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          • #6
            Re: Cant get mercruiser 4.3 in time!!!!!!!

            ...check your dampner, it may have slipped on its mount (draw a chalk line across face and run the engine to detect movement).
            Eddie Petty. #3 Dirt Modified
            Courtland, Virginia
            V-20 Wellcraft
            3.7 470 Mercruiser

            Stumpnocker
            25 Yamaha, 25 Johnson, 25 Evinrude, 9.9 Evinrude, 4 Johnson, 2.5 Johnson

            Comment



            • #7
              Re: Cant get mercruiser 4.3 in time!!!!!!!

              Pointing to where number one is on the dist cap and number one cylinder is at tdc, no matter wich way i rotate the dist cap it will not run properly. all the way one way it wont even start it will only start if it is rotated all the way counter clockwise that it allows me to turn it. This might be far fetched but could this be the issue......

              i have heard that the higher the compression the hotter spark is needed if the engine will run at 25 deg before tdc (piston hasnt compressed the air fuel mixture completly) but wont run at 8 deg btdc full compression. in theory if it was a week coil sending a week spark it might not be enough spark to ignite the air fuel mixture at full compression......

              Comment



              • #8
                Re: Cant get mercruiser 4.3 in time!!!!!!!

                Originally posted by ussoldier_1984 View Post
                ......Pointing to where number one is on the dist cap and number one cylinder is at tdc, ......

                ......#1 @ tdc: Now is that on the compression stroke or exhaust stroke?
                Eddie Petty. #3 Dirt Modified
                Courtland, Virginia
                V-20 Wellcraft
                3.7 470 Mercruiser

                Stumpnocker
                25 Yamaha, 25 Johnson, 25 Evinrude, 9.9 Evinrude, 4 Johnson, 2.5 Johnson

                Comment



                • #9
                  Re: Cant get mercruiser 4.3 in time!!!!!!!

                  compression stroke, and I have never pulled the dist out. it was running great last month prior to me having an issue with my oil pressure switch.

                  Comment



                  • #10
                    Re: Cant get mercruiser 4.3 in time!!!!!!!

                    ...try post #6 !!!
                    Eddie Petty. #3 Dirt Modified
                    Courtland, Virginia
                    V-20 Wellcraft
                    3.7 470 Mercruiser

                    Stumpnocker
                    25 Yamaha, 25 Johnson, 25 Evinrude, 9.9 Evinrude, 4 Johnson, 2.5 Johnson

                    Comment



                    • #11
                      Re: Cant get mercruiser 4.3 in time!!!!!!!

                      When you recently had an issue with it not starting, would it just up and not start? period? So then you replaced the cap, rotor, wires, plugs, replaced all the fuel lines, fuel pump and rebuilt the carb just because? Does it have a fuel water separator? Was it replaced? Then it still wouldnt start till you replaced the oil pressure sensor but it was out of time so THEN you set it to 8degrees? What was it set on before?

                      You need to make 100% sure that you have those wires on correctly. Nothing wrong with the timing light? How did you verify piston 1 is TDC with the rotor pointing to wire #1?
                      1990 Stardust
                      -Dual Chevy 305's with Volvo DP's

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                      • #12
                        Re: Cant get mercruiser 4.3 in time!!!!!!!

                        Thanks didnt see that I will deffinitly check that tomorrow..... But the engine will not run good at all when the dist is in the small window of adjustment that i can turn the dist which tells me that chances are it didnt move on me. i was out on the lake today to try to tune it by feeling how the engine runs then i was gonna fine tune with my timing light. no matter where the dist was it would not run properly it would stall and hesitate and no power at all.

                        Comment



                        • #13
                          Re: Cant get mercruiser 4.3 in time!!!!!!!

                          Use a vacuum gauge to time it.

                          Hook it to a manifold vacuum port then start the engine, at idle set the timing to reach the highest vacuum you can, then retard the timing until you go back down one inch of vacuum. So if your highest is 18 then set it at 17.
                          This will get you close as you can be.
                          As long as the advance curve in the dist is correct, you done.

                          You can recheck it with the light just to see where the marks are if you like. But only use one of the methods to set it.
                          2011 Triton 190 Escape SE 150 Mercury Pro XS

                          I never learned much from winning, but always learn from failure.
                          Semper Fi

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                          • #14
                            Re: Cant get mercruiser 4.3 in time!!!!!!!

                            i did everything because I just got the boat and wanted to make sure everything was up to par. but i knew I had an ignition issue. The boat was originally good and ran at 8 degrees I losened the dist cap when i was checking the time in case i needed to adjust but it was perfect at 8 deg. I lost my balance and accedently rotated the dist a bit throwing it out of time.

                            Comment



                            • #15
                              Re: Cant get mercruiser 4.3 in time!!!!!!!

                              Originally posted by ussoldier_1984 View Post
                              Pointing to where number one is on the dist cap and number one cylinder is at tdc, no matter wich way i rotate the dist cap it will not run properly. all the way one way it wont even start it will only start if it is rotated all the way counter clockwise that it allows me to turn it. This might be far fetched but could this be the issue......

                              i have heard that the higher the compression the hotter spark is needed if the engine will run at 25 deg before tdc (piston hasnt compressed the air fuel mixture completly) but wont run at 8 deg btdc full compression. in theory if it was a week coil sending a week spark it might not be enough spark to ignite the air fuel mixture at full compression......
                              When you say it won't allow you to rotate it any further; is it hitting something physically. Do you need to pull the distributor and rotate one tooth to get the adjustment needed?

                              Comment

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