2020 SX195 motor has a miss

[KirkM]

My SX195 has 40 hrs. When taking my boat out I have a distance to go at 3500 rpm idle (30 minutes) before I can hit the throttle. The motor at higher speed will start breaking up and I have to slow down and re-accelerate multiple times before it runs properly. What could it be? Do you think it could be a coil pack?

 

[Thermobrett]

My SX195 has 40 hrs. When taking my boat out I have a distance to go at 3500 rpm idle (30 minutes) before I can hit the throttle. The motor at higher speed will start breaking up and I have to slow down and re-accelerate multiple times before it runs properly. What could it be? Do you think it could be a coil pack?

Have you recently changed the spark plugs, or checked to make sure they have the correct gap? I would check this before looking into a coil pack replacement. This may be a cheap fix and an easy place to start troubleshooting.

 

[Cobra Jet Steering LLC]

40 hours in 3+ years , when is the last time you put fuel in it?

 

[g2griz]

Our 2020 SX-190 has similar hours and was also running poorly at low & high rpm. Changed the plugs and switched to ethanol-free gas with stabilizer (Fuel Med Rx). Runs great now.

 

[Scottintexas]

many years ago with the mr1 engine we had a couple members who ran long idle stretches that reported their plugs becoming fouled very quickly,
we haven't heard any mention of that in a while though

in your case,
I would certainly think plugs before coils, we see plugs be the issue about 20:1 vs coils

but I would agree with Jeff, I could easily believe you had some bad fuel and when it really gets a suction going, it's picking up the bad stuff,

 

[Thermobrett]

I also heard old/dirty fuel or non “premium” fuel creates issues with the supercharged engines. I always made sure I put in 91 or higher and during our florida “off season” did a fuel treatment.

 

[FSH 210 Sport]

Your boat is three years old, and 40 hours in three years is not very many hours, which begs the question how old is the gas that is in your tank? Was it treated at all? Was it non ethanol or ethanol laced? Does it reach 7400 rpms when wide open ?

I agree with the others that THE most likely cause is the spark plugs. BUT, if the gasoline is as old as it I think it might be that could very well be your problem as well, and if it was ethanol laced fuel that was not treated that could also be a problem. It sounds like a classic case of ethanol fuel that has experienced phase separation.

In your case, I would suggest, A-replace the plugs with brand new properly gapped plugs, and B-re filling the tank WITH ethanol laced fuel and add some fuel system water remover in the dosage required for the full tank, as well as Star Tron and enough Techron fuel system cleaner for the full tank of fuel and go out and burn that tank of gas out at at least 6500 rpm, with some extended runs (at least 5 mins) full throttle. If the engine runs totally fine after that then refill with non ethanol fuel if available, if only ethanol laced fuel is available be sure and treat properly with Star Tron additive.

If this does not solve the problem you will probably have to either have the fuel injectors ultra sonically cleaned or replace them, but by your description it does not sound like you have fouled injectors.