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1986 Mariner 90 HP won't REV Up under load

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  • 1986 Mariner 90 HP won't REV Up under load

    My Outboard is not reving over 2500 RPM when in the water.I've replaced the following already.Rebuilt Fuel PumpReplaced fuel lines, primer bulb, fuel filter,lower unit lube, installed fuel water seperator,replaced the fuel, replaced the oil in the injector reservoir, replaced plugs.I haven't yet rebuilt the carbs. Should I?Its the same prop I've always have used and this new symptom occured this year after storage. I store the engine outside under cover and always foam the cylinders, fuel stabilizer, and leave the fuel tank full and replace plugs each year.This doesn't appear to be linkage related since out of th ewater it revs up fine. Its a load issue still.

  • #2
    Re: 1986 Mariner 90 HP won't REV Up under load

    Bob,I have experienced the same problem 3 weeks ago on my 1986 Mariner 90hp outboard, idles perfectand revs great in neutral. When I was in the water and gave throttle, increased the RPMs, engine just bogged down. I did the same replacements and repairs as you. Gave up and took to repair shop. they think it's a dead coil or switchboxI'll let you knowJr


    • #3
      Re: 1986 Mariner 90 HP won't REV Up under load

      Last night I verified each cylinder is firing. I did this with a timing light while turning the engine over.I pulled the plugs. The Bottom cylinder was pretty clean, the middle had a little buildup, and the top had the most. Not alot though.A compression test revealed 98, 100, and 100 lbs of pressure from bottom cyl. to top. The readings were holding steady.Prop was verified as being tight and not slipping. Its not a press fit hub. Its one of the newer multi-part interlocking hubs. (sorry don't know the names)Would anyone suggest that now I should rebuild the carbs?Also, if the coil is strong enough totrigger the timing light's pick up: is it sufficient to say they are sparking well enough?