Black soot around exhaust port on one engine

[04cobra23]

Happy Saturday fellas.

Took my boat out today and everything seemed to be ok. I opened it up a bit since its been 6-7 months since the boat has seen more than 2k Rpms. Brought it up to 4100rpm for a few seconds. When j got back to the dock and started to wash her down I noticed a lot of soot around the starboard motor exhaust port and nothing on the port side exhaust. Should I be concerned?

thanks

 

[04cobra23]

Anyone?

 

[av8ingtom]

I would not be concerned. I see the same thing on my transom after the boat has been setting all winter. I do fog my engine, and add plenty of stabil before putting boat away for the winter. The soot should go away after a few trips.

 

[scoflaw]

Check for a high fuel pressure reading at the rail.

 

[skunkman]

Almost for sure it is unburned gas passing into the exhaust system and being turned into soot by your cats. It probably occurred because you gunned it to WOT. Ease into higher RPMs and see if the problem persists.

 

[04cobra23]

Morning. Took the boat out yesterday and again the black soot around the exhaust port. I had the plugs recently changed on this motor. The other motor port has zero soot. Any suggestions is appreciated.

 

[CliffA]

Morning. Took the boat out yesterday and again the black soot around the exhaust port. I had the plugs recently changed on this motor. The other motor port has zero soot. Any suggestions is appreciated.

I would check to be sure the correct plugs were used and that they were gapped properly.....

cliff

 

[04cobra23]

What about a bad injector?

 

[KevinS]

I experienced this and it turned out to be the oil coolers - found out after changing plugs, etc. Check oil levels for a hint but if not changed in recent history worth replacing.

 

[04cobra23]

I was told to check;

Plug wire (one may be off)
Temp sensor faulty
IAC sensor
Injector
Bad plug

If I have time this weekend I am going to check the wires and maybe pull the plugs..

 

[Jimmy Buoy]

Like others, I have slight line of soot around my thu hull exhausts after running at normal cruise, but nothing like you have! My question - what are you running WOT port vs stb RPM's? You may find that the "sooty" engine doesn't run as high an RPM as the non-sooty one. These engines are quite good at compensating for weak performing cylinders by boosting the fuel to the others. As already mentioned, a bad plug or two can cause this condition.