Lost power the other night

[Matty]

So I got the boat working... rectifier was the charging system problem. Out for a nice ride the other night and out of nowhere it was like a lost a cylinder or 2...just a cough and sputtered. Limped in to harbour at idle(which was fine). Checking the plugs and coils...coils seem rusty but not too bad and no cracks, plug are the same across all 3, but I'm no plug reader(see pics) Any ideas? I know the supercharger was redone in 2014...but unsure of washer upgrade. Oil is clean and still clear.

 

[Kevin hughes]

What did you find wrong with your boat? Just curious

 

[Matty]

Nothing yet. Haven't had time to dig in! I'll definitely let everyone know when I figure it out!

 

[Cobra Jet Steering LLC]

how old is your fuel? and how is your exhaust system, if you have the bellows they may be leaking into the hull and recirculating exhaust fumes into the engine intake . Had that problem with sea doo 4 tec in the past.

 

[Matty]

Was a fresh tank of 90 from an in Town station. Ran fine for an hour or more and then the 3/4 throttle hesitation started...pulled back and idled in.

 

[Matty]

Sorry I thought I had seen your hole post. So no real accumulation of water other then from rain, so not sure about bellows?

 

[Cobra Jet Steering LLC]

How old was the fuel that was in the tank before you filled up this looks like bad fuel , those plugs look weird , like rust. I would get a 5 gallon water bottle that you can see through and pull fuel from the bottom of the tank , allow it to sit in the bottle and look for water settling in the bottle. If you have water in your fuel tank it will run ok until the movement of the boat mixes it with the fuel and then you start getting that mix into your injectors and cylinders that is when the engine will slow down and run rough or just quit if there is enough water in the fuel . All 3 of your plugs look the same so the most likely common denominator is the fuel.

 

[Matty]

It was tops a half tank of 2 week old gas

 

[Cobra Jet Steering LLC]

Ok you may have purchased bad fuel. it sure sounds like that is the problem or the fuel vent is clogged and creating a vacuum holding back the fuel flow .

 

[Matty]

Ok I will check. It was a brand name fuel station (here in Canada), on the main Street. Anyway I'm going to grab new plugs and I'll toss some Octane boost to help the fuel. Need to try some stuff soon as it's getting cold up here and I will have to winterize it. Going to pull the pump to check the wear plate and possibly go with a lower pitch impeller.

I'll let you know

 

[Cobra Jet Steering LLC]

Ok see how that effects it. But if it has a lot of water in it you will see the same thing as you drive the engine will run worse, the other thing I mentioned is a mesh attachment just after your exhaust manifold called the bellows you can look at it on a parts list. This was a bad design in my opinion.
if you loose a motor mount and " this is a very common problem with those engines" the engine can and will jump around causing stretching of the stainless mesh of the bellows then exhaust and water will blow out of the bellows as the engine runs fast , this reduces the top end of the engine but it usually does not slow down to an idle or go real slow it just kills the top end due to lack of oxygen available for the engine .