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  1. #1
    Join Date
    May 2017
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    Bordeaux, France
    Posts
    7

    Default Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    Hi guys !
    Please excuse possible unprecise terms, since English is not my mother language.
    My engine runs very roughly and has no power when put to gear. Looks like severe missfiring.
    Idle timing is set (at cranking speed) to 2 ATDC and 24 BTDC for max. speed.
    I get sparks on the 3 plugs, (rather white-yellowish than blue), even with spark tester set at 7/16 in.

    Following electrical measurements seem to be OK (Clymer manual)
    - Trigger : 1.2 Kohms on the 3 circuits
    - Stator : 30 ohms (red to gnd) - 1.4 Kohms (blue to red) - Low Speed : 272 DVA - High Speed : 16 DVA
    - Switch box : - stop circuit 265 DVA - Bias 4.5 VDC
    - Coils : primary 0 ohm (meter sensitivity too low) / secondary : 935 ohms (all coils)

    BUT, DVA values of Ignition coils primary input (green wires from switch box to gnd) are VERY wrong.
    When measured at cranking speed (600 rpm) as for above other values, the meter rises slowly from 5 to 15 DVA, instead of min. 150 DVA
    At higher speed (around 1500~2000 rpm), the value raises slowly to 30 DVA.
    When disconnected from the coil, reading from green wires to gnd gives a 285 DVA value, but without any load, I doubt this value has any meaning.

    I cannot understand how sparks can be produced with such a low voltage applied on a coil.

    According to the various trouble shooting guides (Clymer, CDI) the switch box is defective, and I was ready to buy a replacement.
    But according to a couple of marine repair shops I asked for the part and questionned, since the engine can start, and I get such sparks, the switch box is NOT defective.

    I point out that the fuel system is OK. Pump, carburetors, synchronisation have been checked. Idle mixture screw is set to default (1-1/8) and may need to be adjusted, but I do not believe this is so important. It cannot be done anyway before the engine runs properly.

    I would be very grateful if anybody could confirm / justify whether this switch box needs to be replaced or not.

    Thanks a lot for your attention, and have a good day.

  2. #2
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
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    15,200

    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    Sounds like the switch box is not putting out enough amps to fire the plugs under pressure (in the cylinders). You MUST see a robust BLUE spark--orangeypark doesn't not do it.

    Jeff

    PS: Your English is much better than some "Americans" who post here.

  3. #3
    Join Date
    Sep 2010
    Location
    ontario
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    13,669

    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    What does a compression test show ?

  4. #4
    Join Date
    Apr 2016
    Location
    barnegat NJ
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    2,707

    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    run a compression test Octopus33

  5. #5
    Join Date
    Nov 2011
    Location
    tennessee
    Posts
    2,581

    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    The capacitor in switchbox could be damaged or the internal rectifier failing....
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  6. #6
    Join Date
    May 2017
    Location
    Bordeaux, France
    Posts
    7

    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    Thanks, Jeff, for your reply.
    If I try to understand what happens, I would say :
    - the proper DVA enters the switch box
    - the triggers direct it properly to the 3 coils (the timing is OK on 2 and 3, +/- approx. one degree vs. cyl. 1 settings.
    - high DVA can be measured on the disconnected green wires
    - when green wires are connected to the coils, there is strong voltage drop due to un-sufficient amps.
    This would mean that there is a kind of power lost in the box. I checked all wires of the box but did not find any leak to gnd.

    Any comments ??

    The sparks do not look very blue, but it is difficult for me to read the colour. I tried a comparison on my car, but did not find an obvious difference !

    Well, the best is probably to replace the box and hope it solves the problem. As I read on the forum, the box cannot be checked but is supposed to be defective if all other items are OK. This seems to be pretty much the case..

    Will let you know

  7. #7
    Join Date
    May 2017
    Location
    Bordeaux, France
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    7

    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    Quote Originally Posted by racerone View Post
    What does a compression test show ?
    Cyl. 1 - 7.9 bar (115 psi)
    Cyl. 2 - 8.1 bar (117 psi)
    Cyl. 3 - 8.0 bar (116 psi)

    Seems to be normal.

  8. #8
    Join Date
    May 2017
    Location
    Bordeaux, France
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    7

    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    Quote Originally Posted by johnnygjr View Post
    run a compression test Octopus33
    Cyl. 1 - 7.9 bar (115 psi)
    Cyl. 2 - 8.1 bar (117 psi)
    Cyl. 3 - 8.0 bar (116 psi)

    Seems to be normal.

  9. #9
    Join Date
    May 2017
    Location
    Bordeaux, France
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    7

    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    Quote Originally Posted by faztbullet View Post
    The capacitor in switchbox could be damaged or the internal rectifier failing....
    In this case, it might be the cause of what I outline in my reply to Fastjeff below.
    I don't think there is any way to check these components through the wires of the switchbox. Correct ?
    Do you see a way to confirm box failure ?

  10. #10
    Join Date
    Nov 2011
    Location
    tennessee
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    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    Only way to test is to replace...Here is simple way ADI ignition works. Stator charges capacitor in switch box, trigger tel it when to fire.If voltage going in is correct per spec's and volt out is not then the box is problem.
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  11. #11
    Join Date
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    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    Lots of those switch boxes on eBay--and damn cheap! You can score one for 50 bucks if you take your time.

    Jeff

  12. #12
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    May 2017
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    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    Quote Originally Posted by fastjeff View Post
    Lots of those switch boxes on eBay--and damn cheap! You can score one for 50 bucks if you take your time.

    Jeff
    Do you mean for a new one or used ?

    The cheapest new one I saw is at USD 158.95 for an ArielTek (Brasil). Do you know this brand is OK ??
    The cheapest used one was at approx 100 bucks.
    Do you know whether the exact index (A2....A8) is important ? My box is 19052 A7. Mercury vendors quote a 19052 A8 for my S/N.
    I guess all new models replace all ancient versions, but I don't know how different are ancient used versions.
    Have you seen a 50 bucks offer recently ?

  13. #13
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    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    Okay; so I was a bit optimistic, but there's lots of used ones on there for well under 70 bucks.

    A used one? Why not? Unless it's defective you'll have the answer you seek. I've bought several on eBay and not one has been defective.

    Jeff

  14. #14
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    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    Quote Originally Posted by fastjeff View Post
    Okay; so I was a bit optimistic, but there's lots of used ones on there for well under 70 bucks.

    A used one? Why not? Unless it's defective you'll have the answer you seek. I've bought several on eBay and not one has been defective.

    Jeff
    I have received my new switch box yesterday. Unfortunately, no change !!!
    Voltage is still very low, same as before, at coil primary. The engine runs as before, with quite a bit of smoke, and sounds like misfiring.
    Anyway, all documents mention I should get at least 150 DVA at coils, and I only get 15. Again, all other voltages coming from stator and triggers are within spec's, so since the switch box is not the problem, the only remaining components are "downstream" i.e. the coils, the plug wires and the plugs !
    However, I cannot believe that 3 coils fail at the same time (low voltage is same on all 3). And I do not see how the plugs or wires could cause this voltage drop.
    I cannot check the coil primary resistance which is said to be 0.02~0.04 Ohm. My meter is not sensitive enough. At Ohms setting, it reads 0.1~0.2 Ohm and at continuity setting, it rings for continuity ! 0.02 is too close.
    Which item can cause the ignition voltage to drop down ?? Otherwise, am I on a wrong way ??
    I am totally lost. Any idea ?? Thanks for help...

  15. #15

    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ?? Hey did u figure it out

    Quote Originally Posted by Octopus33 View Post
    I have received my new switch box yesterday. Unfortunately, no change !!!
    Voltage is still very low, same as before, at coil primary. The engine runs as before, with quite a bit of smoke, and sounds like misfiring.
    Anyway, all documents mention I should get at least 150 DVA at coils, and I only get 15. Again, all other voltages coming from stator and triggers are within spec's, so since the switch box is not the problem, the only remaining components are "downstream" i.e. the coils, the plug wires and the plugs !
    However, I cannot believe that 3 coils fail at the same time (low voltage is same on all 3). And I do not see how the plugs or wires could cause this voltage drop.
    I cannot check the coil primary resistance which is said to be 0.02~0.04 Ohm. My meter is not sensitive enough. At Ohms setting, it reads 0.1~0.2 Ohm and at continuity setting, it rings for continuity ! 0.02 is too close.
    Which item can cause the ignition voltage to drop down ?? Otherwise, am I on a wrong way ??
    I am totally lost. Any idea ?? Thanks for help...
    Did u figure it out I'm having same issues

  16. #16

    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ?? Hey did u figure it out

    And I put New stater switch box voltage regulater trigger coils plugs wires fuel pump rebuilt carbs out of options

  17. #17
    Join Date
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    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    I can't believe you have three bad ignition coils, but that's all that is left!

    Jeff

  18. #18
    Join Date
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    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    Coils rarely go bad......
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  19. #19
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    Sep 2003
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    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    Especially all three at once, but what's left?

    Jeff

  20. #20

    Default Re: Mariner- 1997 50 HP 2-Stroke 3-cyl. Switch box defective ??

    At this point, I would not know what to say.

    I would start to believe you have a grounding issue (ie. resistance caused by a corroded or poor ground). Or some corroded crimp connections (between the crimp and lug).

    I know when I started working my '86 - 60 hp Merc. I found some wires that had corroded to the point where they had only a few strand of wire left in them.

    I would replace all the wire segments between the CDI box and ground and coils.

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