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Electrical issue with 85 Force 85hp Prestolite Ignition

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  • Electrical issue with 85 Force 85hp Prestolite Ignition

    Hello Everyone,

    I have an electrical issue that I am not 100% is one of my power packs. When I start the motor I have to keep it in fast idle to keep it from stalling. It will start and be revving at about 2000 rpms and then it bogs down to around 1000-1100 rpms. When doing this I put an inline spark tester on and it seemed that the bottom cylinder would be getting a very weak spark when the rpms dropped. I switched the power packs around so that the one powering cylinder 3 was on 1 & 2 then put the one powering 1 & 2 on cylinder 3. The motor would fire for a second and die. I couldn't even get from the ignition back to the motor it died so quick. Switched everything back and it fired back up with the same symptoms.

    My question is does this sound like a power pack issue to you because it does to me. The stator also comes to mind, but what are your thoughts? I did do a resistance check to the stator per outboard ignition.com and it checked fine.

    Here is a list of things already done to eliminate other issues or potential issues:
    Compresssion is good on all cylinders.
    All new fuel lines.
    New fuel filter.
    New fuel pump diaphram, check valves, and gaskets/seals.
    Rebuilt all carburetors.
    New Rectifier
    All ground and wire connections cleaned then dielectric applied.
    New spark plugs.

  • #2
    Sounds that there is and issue with the #2 CDI pack.
    To throubleshoot and get the right result you need a VOM and a DVA adapter to check the output voltage from CDI packs and triggers.
    Outboardignitiondotcom and CDI Electronics have the throubleshooting chart for this.

    If you a bit handy you can made your own DVA adapter, gooole DVA adapter and you get the schematics for one.
    Just some wires, a small box, 1 resistor, 1 capacitor and 1 diod.

    Comment


    • #3
      It does sound like the packs bad
      But, a stator that tests good can still be bad

      You need to test the output voltage from the stator and trigger.

      Try: swapping the bottom coil with #2 coil?
      Try: the trigger, the wires are very tiny and can break easily.
      The ends are shrink wrapped and can hide a broken wire?
      Pull on the wires and see if they separate from the connector?


      Buy American made Cars and Trucks!!!Towing insurance for a boat,a GREAT thing.
      ​Tools to make my life easier: Battery tester, die grinder, temp.gun, compression tester, DVA meter.

      In Scenic , Beautiful San Sebastian by the sea Florida

      88 Bayliner 21CC 2001 Mercury 225 HP EFI

      PLEASE,NO PERSONAL MESSAGES IF THE QUESTION CAN BE ASKED ON THE OPEN FORUM

      Comment


      • #4
        I am not sure if this is a worthwhile test, but I tried it none the less. I tested resistance to the CD pack through the blue and yellow wires. On the CD pack that I believe is good I was able to get a stable reading on the pack that I believe is bad I could not get a reading. My assumption (you know what happens when you assume) is that if they were both functioning correctly the readings would be the same or very similar.

        I did the same resistance test through the coil packs and got a very similar reading for each coil pack, so my hope is that they are all fine. Plus I had moved them around before with no change in running condition.

        I did check all wires and connections, nothing loose or damaged that I notice.

        I ordered a used CD pack from eBay this morning to test out my theory. If it works great! If it doesn't then I am out the cost of shipping the part back for a return.

        Comment


        • #5
          Let us know ??


          Buy American made Cars and Trucks!!!Towing insurance for a boat,a GREAT thing.
          ​Tools to make my life easier: Battery tester, die grinder, temp.gun, compression tester, DVA meter.

          In Scenic , Beautiful San Sebastian by the sea Florida

          88 Bayliner 21CC 2001 Mercury 225 HP EFI

          PLEASE,NO PERSONAL MESSAGES IF THE QUESTION CAN BE ASKED ON THE OPEN FORUM

          Comment


          • #6
            So here it goes...

            I received my "new" to me CD module today, so I took off the CD module supplying my #3 cylinder. This is the one that when I put the ohm/resistance on the blue and yellow wire there was nothing. I tested the "new" CD module when I opened it and it too didn't show any reading on the blue and yellow wires, but I figured it had something to do with the rest of the wires being connected on the motor. After I installed the module, I then fired the motor up and for the first time it sat there and idled for a little while without being in fast idle. However, not long after the motor died. So I tried to start it back up, but it would only start in fast idle and it would drop from about 1800-2000 rpms too around 1000 rpms after a few seconds. I then tested the "new" module to see what the resistance reading was and it was nothing. I went back to the one I took off and it again tested nothing. I tested the other module on the motor that I hadn't changed and it was showing resistance both directions on the blue and yellow wires. So I decided to swap it out for the module I had already taken off that was showing no readings. Buttoned everything back up and hit the key without putting it in fast idle... Fired right up and hummed along for as long as I wanted to let it sit there at about 1000-1100rpms. Thank you Jesus! If I put the multimeter on 20k ohm setting I would get a reading both blue to yellow and yellow to blue. For the other two modules it doesn't matter what setting I put it on the multimeter reads 1.

            I finally got to adjust my carbs close and plan to fully tune them in along with the idle the next time I put it in the water. I have seen a lot of posts that say put the screws at 1 turn out or 1-1/4 turn out. I started at 1-1/4 and adjusted down to 3/4, but the engine didn't really sputter. I didn't want to go less than 3/4. I also went out as far as 1-7/8, but the engine didn't bog down too much. I did run a little rougher once I got past 1-1/2. Right now they are set to 1-1/8 which is right between where I see everyone on this forum saying. Advice?

            Wow this was a journey and I truly appreciate each of you that offered suggestions and advice, thank you!

            Comment


            • #7
              Good to hear it is running now.

              I think the CDI box you now have removed and got it to run have an issue with the blocking diod that is inside the box.

              Comment


              • #8
                Sign up today
                The factory suggests 1 turn out and leave it there.
                1 1/8 is what mine were set at until the factory directive.
                Then it's 1 turn and I didn't see any difference.


                Buy American made Cars and Trucks!!!Towing insurance for a boat,a GREAT thing.
                ​Tools to make my life easier: Battery tester, die grinder, temp.gun, compression tester, DVA meter.

                In Scenic , Beautiful San Sebastian by the sea Florida

                88 Bayliner 21CC 2001 Mercury 225 HP EFI

                PLEASE,NO PERSONAL MESSAGES IF THE QUESTION CAN BE ASKED ON THE OPEN FORUM

                Comment

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