While I do work as a mech occasionally my boss doesn't really take on a lot of Atomic4 jobs so a lot of my knowledge in flat 4 marine engines is lacking. So my problem has involved two mechanics now and myself without a definitive solution so I am hoping some of the old salts here can help me understand.
Near the end of last season I developed an issue while at Catalina island where my trusty little A4 likes to stall after a couple hours of operation and then refuses to restart for like 15-20 min.
Luckily I am friends with the only mechanic on the island and he was nice enough to tow my boat into the harbor and side tie me to his houseboat for the remainder of the weekend. Our best estimate at the time was a dirty fuel filter so we changed it and she seemed to purr like a kitten.
Leaving the island at the end of the weekend she did the same thing to me after taking down the sails and proceeding to my slip. She finally died on me as I was motoring into my slip and she hasnt left since.
Since then I have done the following:
Changed the oil
installed a ballast resistor
checked the fuel vent for vapor lock
Now the old oil was black so no fuel or water seepage taking place there
the old plugs came out black with soot
Upon starting the engine (bearing in mind the last two times Ive ran her in the slip has been at night)
I fire her up and go to turn the water on then run to the back to look at the exhaust. for the first two min or so I get some white smoke and the water coming out has almost a brownish hue. During this time she smells VERY rich or almost like I am burning bad fuel (I did smell the tank and the tank doesnt smell like bad fuel)
After that she seems to lean out with no issues and runs great at lower RPM but feels a little rough at higher rpm's in neutral. I havnt taken her out because I havnt reupped my vessel assist so until I do that a sea trial is out of the question.
The motor running rich would certainly account for the smell and the water and the sooty plugs but doesnt really explain why she stalls out (if the plugs were fouling it wouldnt restart until the plugs were cleaned)
One of the mechanics was saying that I might have a dirty spark arrestor that might be restricting air flow and causing the motor to run rich. (still doesnt explain the stalling issue)
I havnt checked the points yet and the coil is still the same one from before.
I am at that place where I would like to just pull the motor and have her brought back to new but the finances just are not there for me to do that.