2008 excalibur 343 runs rough, ideas to check?

[shag]

2008 230 with 343 excal. about 1100 hrs, always had routine maintenance performed (dealer up to 900 hrs, and me since. Always use ethanol free fuel. Always fresh water use. About two weeks ago engine started, for the lack of a better term, 'loading up' as if it was getting too much fuel. This would cause a rough idle and a noticeable fuelly exhaust smell. I changed cap and rotor and new spark plugs were installed. (both needed it) and actually found a spark plug loose - enough that I didn't need the socket, weird. Plug porcelain looked like running a little rich across all cylinders. Boat starts up quick now but still seems like it is rich. plug cables look fine with no cracks or dryness, ends snap onto plugs well. Batteries kept on a NOCO maintainer and voltage is within normal limits.
My gut tells me it is not fuel system related but ignition related.
Anyone have any input? Thanks in advance

[shag]

Anyone?

[DealsGapCobra]

If it’s running rich, and it sounds like it is, it must be increased fuel or decrease air.


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[Infinity]

Not real experienced in this area, but have you cleaned the spark arrestor at intake and changed fuel filters recently?
Its very possible the AIC is going bad, that can cause engine to run rich if its not opening all the way.
May also be worth checking fuel pressure

You cant always tell if the plug wires are good/bad by looking at them and a bad wire can cause other issues. You can ohm the wires to test the continuity and during test, wiggle the wires to see if it changes continuity which tells you if there are any internal issues that cant be seen.

[shag]

AIC? I should probably know what this is but can't shake the cobwebs off lol. Intake spark arrestor is clean and fuel filters last year with only about 100 hours of use on them.. Only non-ethanol fuel from good source. New high and low pressure fuel pump about 150hrs ago... Probably will get some new plug wires to see. Also just thought - seems as though my temp gauge hasn't been warning up as it should... Going to check it again the digital in the gauge cluster... I am surprised the CC only designed the hour meter to go to 999 on this boat.. lol

[NautiqueJeff]

Have you been through this?

https://www.planetnautique.com/vb5/f...eshooting-info

[MTRBTR]

If your temp gauge isn’t warming up there is a good chance your thermostat is stuck open which would cause the boat to run rich when it is cold.

[shag]

Actually now that I think about it, the temp gauge has been not really moving... Going to compare it to the dash electronic one Sunday and see if it matches... Makes sense.. Jeff, I went through that issue a few years ago and ended up replacing both pumps. I am hoping this is just a stuck thermostat..

[Infinity]

AIC (Air Idle Control valve) was a guess since you mentioned rough idle. It controls the air mix at idle and if not working right can cause the engine to run rich.
Not real familiar with its exact operation but believe its usually mounted on the throttle body and you can disconnect it (there is a plug on it) to see if its functioning properly.

[shag]

Temp gauge is not reading, but the display when using the tack gauge reads 150 after a warm up......

[DealsGapCobra]

If you are saying the electronic temp sender is not working, I would replace it. I’m not sure if the computer uses this sender, but if the computer thinks that it has not warmed up, that might explain the rich condition.


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[shag]

So now to find the temp sender for the small dash gauge....

[MTRBTR]

Think it’s on the water pump on the front of the engine

[8urchvy]

Just posted a reply on your other thread. You should do a compression test. Might be a bad valve.

[shag]

Just an update. No compression in #3 cylinder, dealer pulled head and found "mushroomed" valve (going to have a look today)... Not exactly sure what they're describing but sending head to machine shop to be repaired... Estimate around $1500 parts and labor total... Of course most of that is labor...
Everything else checked out fine.. Cylinder and piston fine, and all other cylinders in good shape with excellent compression.