1986 Mariner 90 HP won't REV Up under load

[Bob Blair]

My Outboard is not reving over 2500 RPM when in the water.<br /><br />I've replaced the following already.<br />Rebuilt Fuel Pump<br />Replaced fuel lines, primer bulb, fuel filter,<br />lower unit lube, installed fuel water seperator,<br />replaced the fuel, replaced the oil in the injector reservoir, replaced plugs.<br /><br />I haven't yet rebuilt the carbs. Should I?<br /><br />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.<br /><br />This doesn't appear to be linkage related since out of th ewater it revs up fine. Its a load issue still.

 

[JRBTS]

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

Bob,<br /><br />I have experienced the same problem 3 weeks ago on my 1986 Mariner 90hp outboard, idles perfect<br />and 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 switchbox<br /><br />I'll let you know<br /><br />Jr

 

[Bob Blair]

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.<br /><br />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.<br /><br />A compression test revealed 98, 100, and 100 lbs of pressure from bottom cyl. to top. The readings were holding steady.<br /><br />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)<br /><br />Would anyone suggest that now I should rebuild the carbs?<br /><br />Also, if the coil is strong enough to<br />trigger the timing light's pick up: is it sufficient to say they are sparking well enough?