Loss of power / won't reach WOT

[Vikingstaff]

Awesome News.

Albeit the repair is not cheap, it sounds like a new boating experience for the two of you. $425 is cheap for a new boat.

 

[Tin Diesel]

Wow at least 6 years without changing the plugs. I bet you won't do that again.

Do plugs on marine engines have a significantly shorter life than on automobiles?

$425 is cheap for a new boat.

That was my wife's comment too! Obviously great minds think alike!

 

[Tin Diesel]

Just beating this topic to death, but I was wondering what the Guardian system was reacting to on the bad plugs. Might help all of us to understand this better.

This is from the Mercury spec sheet on the engine, detailing what the Guardian system monitors:



So, I'm guessing the bad plugs must have been triggering the "Knock Control"?

 

[SEMPERFI8387]

Do plugs on marine engines have a significantly shorter life than on automobiles?

I would think they would foul more, as cars idle very little then get driven at typically higher rpms and burn off accumulating fuel deposits. I would think boats idle more and run at lower rpms vs the short periods of WOT or higher rpms that cars see.

 

[BigKahuna]

Something to ponder......... https://www.championautoparts.com/P...d-maintenance/boat-engine-spark-plug-gap.html

 

[DanV]

I have a 2005 2575rls 5.0 alpha 1 gen 2 and had to get a new outdrive. Thinking we had 1.47 ratio before. Marina put MC-GC-161-N Outdrive Assembly on which im thinking 1.61 by the part #. Have the 17p mirage and only pulling 4200rpms @24 mph now and kid is not happy tubing. Thinking i need to drop pitch to recover some rpm and speed. Just looking for help LoL...