90 Hp Mercury will not power up to full power

[Denny of Pa]

Greetings,

Wonder if someone could suggest some "simple" possible answers, to a power problem. My 90 HP Mercury 2003, seems to start easy and seems to run fairly smooth , however it just will not power up to full power. It use to run my boat at about 40 MPH, but the most it will now go is about 30 mph. Could it be that it is only firing on 2 of the 3 cylinders. ? or would it run rough if that were the case ? but if that is possibly the case ,,, how can I check to see which cylinder in is not firing on ?

I would rather not take it to a marina if it could be as simple of a problem as changing a spark plug,, but since I am not that great of a mechanic, I am not certain how to diagnose the possible problem.

I would greatly appreciate any advise

Thank you

Denny

 

[Sunfish12]

Re: 90 Hp Mercury will not power up to full power

Buy a spark checker that goes between plug and spark plug wire, costs$6. My 1988 90 ran on two cylinders and you couldn't tell by listening to it, it ran smooth but know power when getting on it.

 

[Denny of Pa]

Re: 90 Hp Mercury will not power up to full power

Many many ! thanks,,, i will do that Denny