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Can I Bypass The Ignition Module on a Thunderbolt V?

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  • Can I Bypass The Ignition Module on a Thunderbolt V?

    Have a 1998 Merc Carb'd 454 w. a TB V ignition. After many months of not running, it couldn't generate spark. Thought it was the ignition sensor but swapped that out and still no spark. So that pretty much means it's gonna be the Module. I have a green/white and a red/white wire coming out of the distributor. Can I just hook the green/white to coil negative and the red/white wire to coil positive and run it like a "normal" old school distributor? I know I'll lose timing advance and it won't run optimal, but I'm just really trying to get it running after putting it back together after a valve job. I'll buy a replacement module later.
    Last edited by San_Diego_SeaRay; January 25th, 2020, 07:18 PM.

  • #2
    no...
    Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

    1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

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

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

    Comment


    • #3
      Run thru the troubleshooting guide

      Click image for larger version

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      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


      • #4
        Originally posted by San_Diego_SeaRay View Post
        .... I have a green/white and a red/white wire coming out of the distributor. Can I just hook the green/white to coil negative and the red/white wire to coil positive and run it like a "normal" old school distributor? ....
        All that will do is fry the sensor. They are designed to run on 5v, not 12, and wouldn't be able to handle the current.

        Check you have 12v on the purple wire. Check you don't have anything grounding the white/green.

        Chris.....
        xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
        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 One Gen II (0W829301)
        (Original - 1972 '165' In-line 6. Previous - 1994 4.3LX)


        Comment


        • #5
          Originally posted by achris View Post

          All that will do is fry the sensor. They are designed to run on 5v, not 12, and wouldn't be able to handle the current.

          Check you have 12v on the purple wire. Check you don't have anything grounding the white/green.

          Chris.....
          OK. I did run through that diagnosis flow chart yesterday. I did have 12V at the coil + and I did generate a spark by tapping the green/white against ground. Didn't check for a short on the green/white so I'll do that today. Thanks!

          Comment


          • #6
            1. You have 2 bad sensors or your not connecting the ground wire
            2. Your distributor isn’t rotating
            3. You don’t have a rotor/trigger wheel installed
            4. You have bad spark plugs, plug/coil wires or distributor cap
            5. You have something faulty in your troubleshooting process
            6. You have a problem that has never been seen before
            Good Luck Muc

            Comment


            • #7
              Originally posted by San_Diego_SeaRay View Post

              OK. I did run through that diagnosis flow chart yesterday. I did have 12V at the coil + and I did generate a spark by tapping the green/white against ground. Didn't check for a short on the green/white so I'll do that today. Thanks!
              Your module is fine.

              Chris.....
              xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
              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 One Gen II (0W829301)
              (Original - 1972 '165' In-line 6. Previous - 1994 4.3LX)


              Comment


              • #8
                Originally posted by achris View Post

                Your module is fine.

                Chris.....
                I almost posted that, but I have been told by other mechanics that they have had the module fail (have not seen it myself) so that it won't advance timing. But that wouldn't cause a no spark problem.
                Good Luck Muc

                Comment


                • #9
                  Originally posted by achris View Post

                  Your module is fine.

                  Chris.....
                  Hmmm. That would be great. I know these TB modules are considered very reliable. And like muc said, if they fail, they probably fail by not providing advance curves, not by a no spark condition. Sigh. OK. I'll have to run through the motions again. It's entirely possible I missed something. Thanks again

                  Comment


                  • #10
                    same boat you were dropping the dizzy in from a 350 for a short time?

                    is the dizzy stabbed correctly?
                    Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

                    1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

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

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

                    Comment


                    • #11
                      Originally posted by Scott Danforth View Post
                      same boat you were dropping the dizzy in from a 350 for a short time?

                      is the dizzy stabbed correctly?
                      Yep, that's right. Same boat.

                      I imagine you mean is the dizzy installed correctly? The process I used was to remove #1 plug, crank until I was on the compression stroke, then use the mark on the balancer to find TDC. Then I installed the dizzy so that the rotor was pointing to #1 cylinder.

                      However, my problem is that I can't get spark out of the coil when turning over the engine. So my thinking is that I didn't really have to get the install "right". Just spinning the engine w. it installed should generate a spark? Thanks for your help.

                      Comment


                      • #12
                        BBC's a mild amount of compression when your 180 out, and a fair amount of compression when your at TDC

                        you may want to double-check that your not 180 out

                        your cranking speed needs to be a minimum of 120 RPM
                        Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

                        1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

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

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

                        Comment


                        • #13
                          Originally posted by San_Diego_SeaRay View Post

                          Yep, that's right. Same boat.

                          I imagine you mean is the dizzy installed correctly? The process I used was to remove #1 plug, crank until I was on the compression stroke, then use the mark on the balancer to find TDC. Then I installed the dizzy so that the rotor was pointing to #1 cylinder.

                          However, my problem is that I can't get spark out of the coil when turning over the engine. So my thinking is that I didn't really have to get the install "right". Just spinning the engine w. it installed should generate a spark? Thanks for your help.
                          Your thinking is correct.
                          You might want to try cranking it with the distributor cap off. You should get spark from the coil. Make sure the vanes on the trigger wheel are all way down in the sensor.
                          Good Luck Muc

                          Comment


                          • #14
                            Originally posted by Scott Danforth View Post
                            BBC's a mild amount of compression when your 180 out, and a fair amount of compression when your at TDC

                            you may want to double-check that your not 180 out

                            your cranking speed needs to be a minimum of 120 RPM
                            Yep. I did feel some compression on the exhaust stroke but kept turning it. There was no doubt it was the compression stroke. Freshly charged dual batteries are turning the engine over at a good clip; gotta be over 120 RPM.

                            Originally posted by muc
                            Your thinking is correct.
                            You might want to try cranking it with the distributor cap off. You should get spark from the coil. Make sure the vanes on the trigger wheel are all way down in the sensor.
                            Doesn't the coil want to "ground out" to the block via the distributor cap? If you remove it, that's quite an air gap.

                            I'll double check the vanes. If there's one person who can overlook a detail like that, it's me.

                            Comment


                            • #15
                              Sign up today
                              if you ground out the coil - it wont ever fire

                              the pulsing of the ground signal to the coil - by the TBV is what creates the spark at the correct time
                              Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

                              1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

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

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

                              Comment

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