Crazy Vibration - Bad Plugs?

[DRock3d]

Starboard engine has always ran a little rough but today it was so bad even my wife noticed something wasn't right and we limped back to the dock in no wake.

The impellers were clear and I replaced plugs a year ago but decided to check them. All but cyl 1 was pretty fouled. After replacing the plugs the engine still ran pretty rough on the hose.

What else should I check?

 

[sunbyrned]

It sounds like you have something stuck in the impellers to me. I know you said they were clear but did you pull them out? If not, I would suggest pulling them and putting them back in. This has worked for me, even when there was no apparent sign of debris. Hopefully it’s something as simple as this and nothing major mechanically.

 

[DRock3d]

It sounds like you have something stuck in the impellers to me. I know you said they were clear but did you pull them out? If not, I would suggest pulling them and putting them back in. This has worked for me, even when there was no apparent sign of debris. Hopefully it’s something as simple as this and nothing major mechanically.

I didn't pull the impeller but now I'm all worried that my ecu is dying causing 3 injectors to remain open and foul these plugs.

 

[Beachbummer]

When injectors are stuck open, usually the extra fuel ends up in the oil, raising the oil level and diluting the oil.

Before you worry too much, check for signs in the oil.

 

[DRock3d]

Pulled the impeller, all clear in there.

I've always found these dip sticks hard to read but oil looks the same as always.

What else could make an engine foul 3/4 plugs?

 

[Beachbummer]

That white plug looks like it's not firing to me, much more than the other 3 looked "fouled" (they don't, just black from doing their job)

Was Coil deeply seated? Spark plug firing when trying to start?

 

[84rzv500r]

That white plug looks like it's not firing to me, much more than the other 3 looked "fouled" (they don't, just black from doing their job)

Was Coil deeply seated? Spark plug firing when trying to start?

I kinda agree... coil? measure for primary and secondary impedance... YDS cylinder spark drop test.... these are 1.8's dark plugs look the same and my MR-1's... I think Yamaha runs their motors safely rich...

 

[DRock3d]

I kinda agree... coil? measure for primary and secondary impedance... YDS cylinder spark drop test.... these are 1.8's dark plugs look the same and my MR-1's... I think Yamaha runs their motors safely rich...

YDS cable on the way, hoping it is just the one cylinder then I can move the coil to check it. Hopefully it smooths out if I drop that cylinder.

Usually my vehicles run the plugs pretty clean so these being super sooty was a surprise to me.

 

[84rzv500r]

yeah i think the difference here is the continuous power rating of Marine (and aircraft/industrial) engines... automotive engines are run on the hairy edge of lean so that emissions are reduced (something about CAFE corp ave fuel econ) and they are not required to sustain rated horsepower continuously... running safely rich while increasing emissions slightly it keeps the cylinders cooler and makes more power safely... There is a relationship between a stochiometric Air Fuel mixture and peak EGT also running rich or lean of Peak EGT is a thing in aircraft engines and since they are often air cooled cylinder head temps are important as too much heat is not good good engine components... however for max continuous power rich of Peak EGT is the way to go... as always...

Standard Disclaimer: I could be wrong and YMMV

 

[DRock3d]

I had a burble tune on my 335is totally for the turbo/cylinder cooling benefits definitely not for the sound ?

 

[Scottintexas]

vibration could also be cavitation,

I would run it on the hose or even on the water without the impeller to isolate if it's the engine or something else,

when my silicone in the intake tunnel came loose it vibrated and shook the boat as it sucked air in under load,

 

[DRock3d]

I'll have to take a look into that, any guides on here for the proper method to apply silicone?

 

[Scottintexas]

https://jetboaters.net/threads/cavitation-missing-sealant-in-pump-grate-fixed.884/

my experience with household silicone, still holding,

this is just a thought, I wouldn't rule out other possibilities,

 

[DRock3d]

Well boys got my first twig. I coulda swore this was the starboard engine and that engine is still a little rough so gotta figure that out still.

I had never pulled the port pump since I've been chasing issues with the starboard engine since I got the boat (some asshole gooked the whole outside of the pump with silicone)

Honestly surprised I didn't see those marks on the cleanout plug, the wear ring looks rough on this side as well.

 

[sunbyrned]

That’s a good sized twig. I think you found your source for the rough engine. What does your impeller look like? Is it dinged up? What do you mean when you say you’re surprised you didn’t see those marks on the clean out plug?(sorry, not following)

 

[DRock3d]

Impellers both look nearly perfect, port wear ring is worse than starboard.

Look in the tunnel you can see a group of gouges that run from the tunnel over the clean out plug.

Starboard tunnel is freshly sealed with a white sealant maybe 5200, port tunnel is a that gross old silicone.

Boat is running strong though, did 50 with the top up so maybe I'm just being anal.