2006 5.7L mpi rich exhaust

I just bought this boat with twin 2006 5.7mpi crusaders with under 1000 hours. Did all the normal tune ups plugs, wires, cap, rotor along with fuel filters.

ran the boat 3 days this weekend and BOTH engines are putting off quite a rich exhaust. At first I could tell the motor was loading up at idle, I fish and plan on using these to troll. I put the engine in neutral and throttled your a bit to see a massive black scheme appear behind the boat. I panicked thinking I was losing oil. Started my port motor and examined my en starboard engines oil. No change, no fuel in oil no water in oil. I then noticed the exhaust on my port motor was also puking out the same junk. I am thinking this might be an old fuel issue but am looking for any additional input on things to check out.

prior owner was not mr maintenance. I have no idea how long the old fuel has been in the boat, but was able to run
back to the dock today pretty hard without any issues but you could still see the sludge coming even at the higher rpm.

checked oil again today no change in levels. Motors both run in the 165-180 degree range as I believe they have 170 stats.

any points in a general direction would be helpful.

injectors may be leaking and need recondition....

would be good to get a scan tool and make sure the other sensor inputs are within expected range, too...

could defiantly see this happening but for both engines to be doing the exact same thing!?! Im gonna try some Techron marine this week and try to freshen up the fuel to see if Anything helps.

makomark said:

injectors may be leaking and need recondition....

would be good to get a scan tool and make sure the other sensor inputs are within expected range, too...

Click to expand...

if they share a common fuel tank (or if two tanks, they both shared a bad batch of fuel), both engines could develop the same situation...

still believe getting a scan tool and verifying engines are 'happy' with sensor inputs (and giving you a baseline) would be worth the effort...and it would help to isolate potential causes - the ECU's don't monitor everything...

yes both engines draw from 1 main tank. Hoping just the process of getting rid of the fuel and freshening up the fuel system will help. Yes I am looking into doing a scan on it from local mechanic.

makomark said:

if they share a common fuel tank (or if two tanks, they both shared a bad batch of fuel), both engines could develop the same situation...

still believe getting a scan tool and verifying engines are 'happy' with sensor inputs (and giving you a baseline) would be worth the effort...and it would help to isolate potential causes - the ECU's don't monitor everything...

Click to expand...