2007 Mercury Optimax 115 Hp missing on one cylinder?

Archer440GR

Recruit
Joined
Sep 24, 2012
Messages
1
I have a 2007 Mercury Optimax 115Hp. that randomly will not throttle up while trying to get the boat up on plane. I throttle back and try again. It coughs and sputters and eventually comes to life. It seems like it is missing on one cylinder. I have changed the plugs and still have the same issue. It seems to be totally random. I am suspecting one of the cylinder coils. Is there any way to prove this out? If I were to take it to a dealer, would they be able to plug into the computer to determine if it is a coil problem on one of the cylinders? I really do not think it is fuel related.
Any thoughts would be greatly appreciated.
Thanks in advance!
 
M

Maxz695

Guest
Re: 2007 Mercury Optimax 115 Hp missing on one cylinder?

Not sure if this engine is fuel injected or carbureted. If carb then try adjusting the air mixture scew in a bit. The other thing that comes to mind is water intrusion. Because the amount of water is small it intermittently causes a plug or plugs to temporarilly foul. If this is the case it iwill get worse and not better. The internl parts of the engine will be effected everytime it,s run. I hope for your sake it,s just a bad coil. Check your trigger wires for wear breaks or cracks. Check the grounds are all tight. Try starting it in a tub of water with low pressure to the LU just enough to make a stream out of the TT. Thrott5le up and see if it persists. If it does chance3s are it might not be water intrusion. Exhaust plate gaskets sometimes leak and let water into the exhaust divider plate. This would go into the cylinder combustion chamber on the power stroke and suck water into the block during the intake stroke. You get the picture
 

Bamaman1

Lieutenant Commander
Joined
May 15, 2011
Messages
1,895
Re: 2007 Mercury Optimax 115 Hp missing on one cylinder?

A 2007 Model Optimax is a high tech Direct Fuel Injected motor. Easiest thing is to find a repair shop or dealer that'll put it on an engine analyzer for 1 hour labor. Hopefully it's throwing a code that'll point you to the specific problem.

Diagnostics is a great benefit of the new CAN/BUS electronics in a modern outboard.

But be sure to get a set price on repairs before you let'em touch it.

I prefer to do business with an independent shop with servicemen that have worked in dealerships and are familiar with modern outboards. Shade tree marine mechanics are essentially a thing of the past on engine work.
 
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