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1986 175 blackmax problems need help

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  • 1986 175 blackmax problems need help

    i have a 1986 champion bass boat with a 175 blackmax outboard on it and the problem i am having is this..... took the boat out 2weeks ago and the boat ran great then last week took the boat back out and as soon as it fire off in the water i could tell something was wrong.....the engine was missing.....got back to the house and fired it up and found 3 dead cylinders, cylinder #2,3, and 5.... checked the obvious and found spark on all 6 cylinders. checked compression and had 125-130 on all 6 cylinders. suspected trigger and changed with no difference on the outcome. changed rectifier with no difference. reversed coils for 1 and 2 to 3 and 4 to isolate the problem and same cylinders still dont fire. checked plugs and plugs are wet so there is fuel getting there......any ideas or help would be great.......

    Checked the bias circuit and seems ok What I did do today was switch the switch boxes to see if the dead cylinders would change, and changed the rectifier. Nothing changed. Still have strong spark on all six cylinders but 2, 3, & 5 won't fire (plugs are also new). I then reversed two of the coil packs for 1&2 and 3&4, again no change. Then fired the motor and lightly sprayed some engine start fluid in the dead chylinders. #3&5 briefly fired, but #1 stubbled. My next move is to tear down & rebuild the carbs, however not sure this is the problem. Sure acts like ignition timeing to me. Just wierd, ran great last time out (two weeks ago) and now this. Maybe if you can explain the indexing issue I can zero this in. By the way, did try a different trigger with no change. Also tried my old stator with no change. Again, the puzzling part is having spark/compression and fuel and these three cylinders don't want to fire. Any thought or suggestions would be greatly appreciated. also did flywheel indexing and checked timing on all cylinders and seems that it all checked out ok

    thanks, Gary in yuma arizona

  • #2
    Sounds like ignition is probably not the issue. Try repairing the carburetors, if you can see the reed valves with carbs removed, inspect.
    Regards
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    • #3
      thanks for the response we are gonna go through the carbs next

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