I’m sucking out a little oil right now because I still think it’s a little too high. I always put 5 quarts in but honestly, I think that’s too much. It puts me over the operating range a bit. I’ll check the fuel pressure hopefully the next 30 minutes and respond back. Ive checked it 1 million times before and it’s been good.

9 minutes ago, kylegansel said:

Temp sensor is about 5 years old.  Could maybe change it out again. Oil level actually seems a bit high.  Could that cause the excess carbon?

Soot is usually unburned fuel.  Oil is more of a spooge as we call it on a two stroke.  If you are burning enough oil to leave black on the boat, you would be using oil quickly and notice you are having to add oil.  
 

the spec is 4 bar on fuel.   That’s 58-62 psi.  Mine ran 55 with a stock 4 bar regulator.  Not hard to check fuel pressure.  

Temp sensor is about 5 years old.  Could maybe change it out again. Oil level actually seems a bit high.  Could that cause the excess carbon?

15 hours ago, kylegansel said:

I realize this post was done a while ago, but I have a 2005 LX and I’m dealing with major carbon. I took it into a dealer and they told me they adjusted the fuel pressure regulator which isn’t possible. All you can do is replace it. I’m running rec 90 Gas and I’m getting carbon all over the back of the boat and the sides of the boat. Any help would be appreciated.

You can buy an adjustable regulator.  Less than $100 off Amazon/eBay. https://www.ebay.com/itm/203105221078  Turns out a 1.8l VW uses the same regulator and they are adjustable.  Btw there is no way for the system to know the mix on an 05.   It’s an open loop speed density type system.  Look at manifold pressure, rpm, throttle position for inputs.  It also looks at engine temperature to enrich for cold starts.  If it suddenly started to run richer, it may be due to a faulty thermostat or temperature sensor.  Some boats have two temp sensors, one for the ecu and one for the dash.   I honestly dont remember how the monsoon is setup.  With the computer hooked up you can easily see the temp that the ecu is seeing to check if the sensor is bad as you say the dash temp is correct at 160.  

Randy

May I suggest you change the title of your post from Randy to the nature of your problem.  MN