Black film on the back of boat

I have a 2001 volvo penta sx 4

I have a 2001 volvo penta sx 4.3gl v6 190 hp after i use the boat there is a black film that is on the back and needs waxing to take it off it is along the water line anyone know why it is doing this any solutions its not dirty water?

"you would be surprised at how

"you would be surprised at how contaminated the water is in and around the boat ramps, the 1st time I backed my boat down just to crank it and let in run never removing it from the trailer,
I pulled the boat back out after running it for about 15 minutes at idle and nottice the same crap your talking about all over the rear of the boat just as you said, I thought to my self man!how could any fish live in this water?
anyway, I'm sure each and every boat contributes to the pollutants of the water,some more than others,, boat ramps are going to have folks that bring there boats out just as I did to see if everything is A-OK after a repair to there engines etc,etc,etc, not to mention the 2-cylce
2-strokers outboards engines! And the jetski's
most of these use the
oil & gas mix and we all know what kinda mess that stuff makes. OH! and a quick removal TIP
of getting this mess from your boat, use a mixture of about 50% 50% purple power and water, takes it rite off, although dont let the purple power stay on the boat for long time,
simply spray it on and wipe right off and rinse
with water, and then I use a misting spray on detailers
cleaner /wax >> you know the stuff you see the car guys use while out at the car shows ,,it will extend the shine in between waxing,
works great for me.."

I thought that it might be bur

I thought that it might be burning rich because it usually is on the back only and not the sides? I cleaned the flame arrester out....it could be the water.....

thanks

"Whenever I troll with my AQ13

"Whenever I troll with my AQ130C engine, I have a black film all over the back of the boat at the end of the day, but when I cruise no film. In my case, I think it's from the exhaust attaching itself to the boat because I'm going so slow (trolling)."

Yeah i think it is the exaust

Yeah i think it is the exaust is that normal? Or is it burning rich?

"Hey I had a 4.3 merc 190 hp a

"Hey I had a 4.3 merc 190 hp and I was always cleaning of the exhaust of the back of the boat mine was not fuel injected I think my friends that had fuel injection didn't seem to have the same problem, the boat always ran great."

Hey joe i have a carburator on

Hey joe i have a carburator on mine also did you ever fix yours? If so what was it?

Mine does the exact same thing

Mine does the exact same thing. I think it's running rich because at times when I start it I see blue smoke. The boat runs and starts great and seems to be very very fuel efficient for a V8. If it is running Rich does it hurt it?

"I dont know if it hurts it bu

"I dont know if it hurts it but i dont like seeing the black film every time i use it...I asked a volvo penta mechanic he told me to clean the flame arrester, spray the carburator with carborator cleaner and see what happends it might be the choke sticking...I have not used it that much since i sprayed the carborator but it seemed to idle better....I have the smoke when i start mine also he said it was normal....."

"I made it a point to look aro

"I made it a point to look around the water level of my boat last time out,ankered off in a calm cove swiming around the boat had no sign of the black
crap, then later on after I had loaded the boat onto the trailer there it was again, around the the rear of the boat,"

"i wonder what it is from? I t

"i wonder what it is from? I taled to a volvo mechanic and he said clean the flame arrester, spray the carb and then see i havent tried it in the water since i sprayed the carb...hopefully it works..Any other ideas?"