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1998 90HP Mariner outboard

NavySailor

New member
Question:
I have a 17' Mako Center Console with a 1998 90HP Mariner 3 cylinder serial # O[FONT=Arial, Helvetica, sans-serif]g748015[/FONT]

[FONT=Arial, Helvetica, sans-serif]I'm a first time boat owner and a rookie to say the least. The motor is shaking (bouncing side to side when at idle) which i'm thinking the mounts are bad, i watched utube on how to tell and they are bad, both top and bottom and severely corroded. i have the IPB's for the R/R of the mounts so no big deal. Just wondering anyone's thoughts on any other possible problems it may be.

Additionally when i throttle up on the control lever, it it kinda delayed.... like it takes up to like 10 seconds for the motor to catch up to the control. What do you think the problem is or is this normal? I know a 90hp isnt going to push your hair back right away but with my experience in A/C maint, usually that means the power cable or fuel problem. Unsure.

What spark plugs and wires are the best to replace the old ones with?

Also is is best to buy Carb repair kits for each carb or just take them apart and clean them first? Is there a specific fuel additive i can use to help clean out the build up and for prevention?
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Sorry for all the questions, just trying to get my motor to where it should be and continue to upkeep.


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I think that you should buy the repair manual for your motor because of all the information you're going to need, use the serial Nr. to buy the right one (there are many) from Mercury. This is the best way to get crucial info.
 
I think that you should buy the repair manual for your motor because of all the information you're going to need, use the serial Nr. to buy the right one (there are many) from Mercury. This is the best way to get crucial info.

Thank you, i'm going to get one for sure just was reaching for everyone's experience. Thanks for your guidance.
 
I'd start by getting the idle mixture reset--it sounds like the motor is running lean on some (or all) cylinders.

Jeff
 
Ok update: compression test is 120/120118
-spark test good
-all carbs cleaned
-replaced spark plugs
-rebuilt fuel pump
-throttle seems much better and response is good.

Motor idles great and sounds good.

problem is once go to full throttle it won’t got past 15mph and is at 3900 rpm
I don’t know what’s causing the lack of power. It sounds and feels like it should but won’t push past 3900 about 14-15mph???? Any suggestions on what I should do next?
 
How would I inspect it and what am I looking for? How would a cylinder sleeve rotate? And how would I check that out? That’s for the response
 
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