90hp Mercury woes

I bought an old 16' Campion w/ 1987 90 HP Merc outboard. Maybe you guys can help me out. When I boiught it, the owner said it just died in the middle of the lake and he was able to limp it to shore. He couldn't figure out what was wrong and bought a new boat. So here I am with a manual, a small amount of knowledge, and I can't figure out why this sucker won't run. I've charged the crap out of the battery and when I turn it over the flywheel rotates 2 - 3 times. To get it to turn over again I have to shut down then turn the key again. First thing I did was replace the plugs (I've got good compression) then pulled the lower leg (looks fine) and the starter is good. I've got the plugs out now and sometimes the flywheel turns a couple times and sometimes it'll roll over like crazy (like it should). I know I'm gonna have to start ripping and tearing but I'm hoping that it's something stupidly easy like an ignition wire that needs replacing. Any ideas would be appreciated. Thx Let me know if you need more info

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Originally Posted by enrico

I bought an old 16' Campion w/ 1987 90 HP Merc outboard. Maybe you guys can help me out. When I boiught it, the owner said it just died in the middle of the lake and he was able to limp it to shore. He couldn't figure out what was wrong and bought a new boat. So here I am with a manual, a small amount of knowledge, and I can't figure out why this sucker won't run. I've charged the crap out of the battery and when I turn it over the flywheel rotates 2 - 3 times. To get it to turn over again I have to shut down then turn the key again. First thing I did was replace the plugs (I've got good compression) then pulled the lower leg (looks fine) and the starter is good. I've got the plugs out now and sometimes the flywheel turns a couple times and sometimes it'll roll over like crazy (like it should). I know I'm gonna have to start ripping and tearing but I'm hoping that it's something stupidly easy like an ignition wire that needs replacing. Any ideas would be appreciated. Thx Let me know if you need more info

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Its sounds like your carbs need a good cleaning, Also make sure there's no water in your float bowls.

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Originally Posted by Kamdyn

Its sounds like your carbs need a good cleaning, Also make sure there's no water in your float bowls.

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I hope there's no water in there, this sucker spent last winter in my backyard freezing his ass off

It's also possible that this guy lied saying he was able to limp it to shore. Maybe he found out it was the pistons or something and how much it would cost and said f%$* it.

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Originally Posted by enrico

It's also possible that this guy lied saying he was able to limp it to shore. Maybe he found out it was the pistons or something and how much it would cost and said f%$* it.

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If your getting good compression than your pistons are okay, The last owner probably didnt want to drop over 500 dollars to clean the carbs, Because that will cost you that much. But when its done it will run like a champ you'll notice it right away, Plus It will start up right away. goodluck with your boat my friend

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Originally Posted by Kamdyn

If your getting good compression than your pistons are okay, The last owner probably didnt want to drop over 500 dollars to clean the carbs, Because that will cost you that much. But when its done it will run like a champ you'll notice it right away, Plus It will start up right away. goodluck with your boat my friend

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Thx Kamdyn, I'm actually heading off to work for a bit...8 months since I last worked (and people think the oilpatch is all gravy, damn recession / global warming / alberta royalty revue) but when I get back I'll rip and tear and report back

How did you test the compression if it wont turn over more than 2-3 times ? Can you turn the flywheel with the plugs removed?

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Originally Posted by StanW

How did you test the compression if it wont turn over more than 2-3 times ? Can you turn the flywheel with the plugs removed?

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Flywheel turns like a bastard without the plugs in. Oddly though, sometimes I'll. only get those few turns, then sometimes it'll keep going. That made me wonder if it could have something to do with an ignition wire??

There is nothing electrical that should really prevent the motor from turning over... Unless the stator is doing something weird. Easy to check out - just requires an ohm meter. Measure fast and low idle .

I should've bought a kayak...way easier to figure out, but a bitch to ski behind

I know this thread has quite a bit of age on it. Did you ever get this rig figured out?

haven't had a chance to yet, work is consuming my life (no complaining though)

check all your electrical connections and clean them well........good place to start simple.....:thumbsup:

Glad to hear you have work.

Was just wondering if you'd had a chance to check this rig out any further? Once you get it cranking it's likely to need the carbs cleaned if it's been sitting for very long. Those old inline six's were great engines and will run forever.

Thanks for the responses and great suggestions guys, unfortunately I've been working tons and only get home to see what the house looks like every once in a while (not a bad problem to have I guess). I just hope I can get to playing with this sucker before the snow starts flying here since there doesn't seem to be any end to the work.

I believe you said you have the service manual, if not get a Mercury manual from a dealer. Once you have a OEM manual clean and set your carbs as outlined in the fuel section of the manual. After you have done the carbs, follow the step by step instructions in the Timing,Synchronization and Linkage adjustment section of the manual and you should be good to go. Most of the problems with outboards are simply because they are not set-up properly. If memory serves, your 90 is a 3 cyl. motor.

6 cyl til 86 and 3 cyl starting with 87 ..... I have a 75hp which is the same engine , shakes and shudders at idle but real smooth once the rpm build up .

i run two 85 hp mercs on two different boats i like the one on bass boat so much i put on on the house boat. it could be as simple as the ball./ mine would run fine in nutral and it would rev up but in the water under pressure i8t would just go dead. it doesn't sound like you'll have to tear it apart. just see if you have fire at plugs when spinng it over. may need new battery or starter. if it won't turn over. if you have fire at plugs compression and fuel it will run. they are great motors. not enough info in thread to ell you much more. sorry hope this helps

i outran the coast gaurd with bas boat.lol i wasn't catching anything so i went across state line up river to get some quart beers. saw the coast gaurd a bigger boat slow down to turn around i was already a mile ahead of him. i went on to truck.lol a freind who i was fishing with lost his hat. he said my hat. i said i'll buy you another on i aint turning around. lol