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  1. #1
    Member Cecil75's Avatar
    Join Date
    Jun 2009

    1996 Mercury 150 EFI - possible coil issue

    '96 Mercury 150 EFI
    Ser.# 0G406555

    Took my boat out Sunday for the first time since mid-summer, it fire right up but when I started to accelerate to get on plane it bogged really bad. When I shifted to neutral it cut off. After that it was hard to start and I would have to throttle up in neutral to get it going just to get back to the ramp. Got home and discovered with an in-line spark detector that #1 and #4 cylinders had no spark. After researching this problem I tried switching the coils and sure enough the problem moved with the coils. Is it common for the coils to go bad just sitting up? I know that it is recommended to change all six coils and I plan to do so. I see OEM coils are around $55 and some Sierra aftermarket coils can be had for $30 or so.

    Does anyone recommend staying away from aftermarket ignition parts? I replaced both of my power packs 2 years ago with CDI packs and they have served me well so far. Also, I've been running NGK BU8H no gap plugs in this motor for many years - is this the correct plug or is there a better option?

    Thanks for any and all responses.

  2. Member
    Join Date
    Oct 2016
    Yes, the surface gap BU8H is the correct plug.

    I highly recommend sticking with OEM parts if possible.
    David Patten
    Automotive and marine technician.

  3. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Greenville, SC (US)
    Unusual to just "lose" two coils like that, but yes, it could happen.

    I would also recommend sticking with the OEM components (and BU8H is a good choice, the factory recommended Spark Plug).

    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 45 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

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