225 Optimax not revving over 2000 rpm

[Gillagorilla]

My parents had the boat out yesterday with both engines running for about 4 hours and they were fine. The Mercury smart gauges for the starboard engine did say at one time that the engine was only running at 63% effecincy at one time. Also before he bought the boat the compression test was done on both engines and they were all 105 or higher and within 10% of each other, but might have been closser. They took it out today and drove it for 2 minutes on plane then backed it down to idle to mess with the gps, after that he tried to get it bac on plane and noticed that the starboard motor lost power. He notced that the engine would not rev over 2000 rpms but everyonce in a while it would rev to 3000 rpms and once to 4000. It does idle fine for docking purposes. So they limped it across the river on the port motor and fired it up to dock but it still would not rev up much.

We have not had a chance to put in some of the maintenance items like the plugs, fuel filter and water seperators yet, they just wanted to make sure it was running good then we would do the rest of the maintenance stuff before it heads over to the bay from the Potomac. My brother did replace the 6 plugs on the starboard motor after it acted up today with still no change, he said the plugs were very carboned up.

They are going to change the filters on both engines and plugs on the port engine tomorrow. Is there any thing else that you can think would cause this before we drop it off at the marine shop?

Thanks for any usefull replies.

 

[WillyBWright]

Re: 225 Optimax not revving over 2000 rpm

Sounds like it's going into Guardian mode. It's a power reduction to save the motor from serious damage due to certain conditions seen by the computer as not favorable. They'll probably need to take it to a dealer to have it diagnosed. But it's possible that it was a transient problem that has corrected itself. If it happens again, reset the motor by turning it off for several seconds and restart. Some problems occur just once and some need repair before it'll give full power again. A dealer can tell what caused the power reduction by connecting a computer to it.

Sooty carboning is normal. You can clean it off with a nylon brush, but nothing more agressive. The plugs have tiny pads on them that come off easily by gapping or cleaning. Without those tiny pads, they don't fire well at all.

 

[Gillagorilla]

Re: 225 Optimax not revving over 2000 rpm

Thanks Willy

For the $17 retail price for the irridium plugs they ought to install themselves. At least we only had to pay $12 bucks a plug but still OUCH.