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3.0 mercruiser no spark problem

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  • 3.0 mercruiser no spark problem

    i have a 3.0 mercruiser in a 1991 bayliner capri 1850 with est ignition that has been sitting for 4 or 5 years, it cranks well with a new battery i put in but i dont have any spark. i have verified all the safety swithes and tach are not the problem i know this is when i un hook the laynard it shuts power off to the coil on the purple wire coming out of the harness, so those things can not be the problem. i but currently i have power coming out of the purple wire into the ignition coil and i have a good ground between the harness and the ignition coil and there is another 2 wire plug coming out of the the ignition coil to the distributor and they both have power with the key on i put on a new distributor cap and rotor due to being pretty corroded. there is still no spark coming out of the ignition coil. i also checked the fuseable link in between the the distributor and ignition coil can anyone verify my thoughts?

  • #2
    Howdy

    Start by disconnecting the gray wire from the boats tachometer. Then disconnect the wires from the shift interrupter. Check for spark again.

    If no spark, look at the last couple pages of the bulletin in the link. It provides some test
    http://www.boatfix.com/merc/bullet/90/90_15.pdf
    94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
    95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
    07 Seadoo GTX
    Merc Adults Only VP Adults Only
    G-Dad always said "First Liar doesn't stand a chance"

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    • #3
      i did all that and everything checks out good. is the shift interuptor supposed to be normallu closed

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      • #4
        and am i supposed to disconnect just the grey wire or the whole tach because mine is all one molded plug on the back

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        • #5
          and the black wire and the white and green wire on the shift interupt have continuity even when the shift switch is not connected and when unplug the power to coil from the harness it loses continuity

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          • #6
            The black on the shift interrupter is ground, the White Green is used to ground the distributor when the shift switch is used.
            The shift interrupter is normally open
            The plug on the tack can just be removed.

            What your trying to do by removing the wires, is to remove everything not needed for the motor to run. If the shift interrupter or the tach shorts out, this will stop all spark
            94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
            95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
            07 Seadoo GTX
            Merc Adults Only VP Adults Only
            G-Dad always said "First Liar doesn't stand a chance"

            Comment


            • #7
              i dont have a white and green on my distributor. just a pink and brown. therea the small plug on the left and larger one on tge right. the larger one is empty

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              • #8
                my shift interupter has continuity across it at all times no matter what position it is in and even when i take it out i still have no spark

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                • #9
                  Originally posted by warrenc123 View Post
                  and the black wire and the white and green wire on the shift interupt have continuity even when the shift switch is not connected and when unplug the power to coil from the harness it loses continuity
                  Originally posted by warrenc123 View Post
                  i dont have a white and green on my distributor. just a pink and brown. therea the small plug on the left and larger one on tge right. the larger one is empty
                  Seems we are having trouble conveying what the issues are.

                  Did you do the test listed in the PDF file which is in the link in post 2 ?
                  94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                  95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                  07 Seadoo GTX
                  Merc Adults Only VP Adults Only
                  G-Dad always said "First Liar doesn't stand a chance"

                  Comment


                  • #10
                    yes i did every step. here are some pictures i hope they help. so far it has a brand new ignition coil., distributor cap and rotor. the boat has 12v at the purple wire going intp the ignition coil all the time. it grounds are clean between the coil mounting bracket and the block. the shift interuptor switch has continuity across the wires. i did all thw tests on the document you provided in post 2. im thinking maybe the ignition module




                    Last edited by warrenc123; May 1st, 2017, 05:34 PM.

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                    • #11
                      Correct me I missed something
                      Have 12V on the positive side of the coil when key is turned ON
                      Disconnected tach and shift interrupter
                      Accomplished all test in PDF and all check good without issues

                      If all the above is correct then I have nothing. Sorry but someone else needs to try
                      94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                      95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                      07 Seadoo GTX
                      Merc Adults Only VP Adults Only
                      G-Dad always said "First Liar doesn't stand a chance"

                      Comment


                      • #12
                        okay. thank you for your efforts. please see post 10 as added some stuff for you

                        Comment


                        • #13
                          Where is this connector?
                          Click image for larger version

Name:	plug.jpg
Views:	1
Size:	78.1 KB
ID:	10386032
                          94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                          95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                          07 Seadoo GTX
                          Merc Adults Only VP Adults Only
                          G-Dad always said "First Liar doesn't stand a chance"

                          Comment


                          • #14
                            i just got the boat it was never there

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                            • #15
                              Sign up today
                              Originally posted by warrenc123 View Post
                              i just got the boat it was never there
                              This one is used to set timing and also connects to the shift interrupter
                              Click image for larger version

Name:	3_0L wiring Diag.jpg
Views:	8
Size:	45.6 KB
ID:	10386051

                              As before, should have 12V on the purple wire, having that and everything else, I just don't know, it should either work, or show why its not
                              94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                              95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                              07 Seadoo GTX
                              Merc Adults Only VP Adults Only
                              G-Dad always said "First Liar doesn't stand a chance"

                              Comment

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