Mercury 50HP 3-CYL 2-stroke Oil Injection Model (2003) Help! (Fuel/oil issue?)

[godblessamerica11]

This boat is new to me. I have had it out over 30 times in the past 4-months. Lucky me, she ran great. A week ago I noticed the motor was not as throaty and actually sounded a bit "slushy." It just didn't seem right. I took it out again days later and had a hell of a time starting it (30mins). When it did start is sounded slushy/tired. It would die shortly after sitting at idle. I warmed it up eventually and got it in gear and was able to move no faster than 10 mph at 3/4 to full throttle.

I am no mechanic:
-The oil reservoir doesn't seem to have moved much - could it be too much gas
-I had fresh gas in tank. In fact I usually treat gas with a stabilizer not knowing when I may take boat out again
-I had new plugs, oil, lower unit lube, impeller installed going into spring
-I was able to smell/see fuel in the water the last time I was out, but I confess I left the motor on choke a little longer than I should have potentially choking her out...

Guys,
any feedback would be greatly appreciated. I am up for learning and working on this motor.

Thanks,
Joe

 

[racerone]

Oil must go down in the reservoir !------So now the first step to take is a compression test.-----Then run with a 50:1 oil mixture in the fuel tank untill you are 100% sure that oil injection is working.----Hopefully it is not too late.

 

[Silvertip]

The engine probably is running on only two cylinders. Pull the plugs and check them. If one is very wet with fuel that's the cylinder not firing. This problem is not from too much fuel but rather not enough spark or lack of oil and a cylinder has lost compression. If the carbs have not been rebuilt in the last few years it is probably time to do so. To check the injection system place mark or tape at the current oil level. Run the boat rather hard for one hour. Now add oil to bring the level back to the tape/mark. A 50 HP engine will burn roughly 5 gallons of fuel per hour at WOT. If it takes a pint of oil to bring the level back up to the mark, the injection system is working.