Re: how do you know if you're getting water in a cylinder on a v4 evinrude?
Remove the plastic air filter (silencer) that covers the carbs so you can see into the carb throats.
Without the motor running, press on the throttle linkage in the motor to see if all of the butterfly plates in the carbs are opening at the same time. If that one cylinder's butterfly plate isn't opening (due to a broken or disconnected throttle linkage), then you may have found your problem. If it is functioning correctly, then look into the fuel side of the equation.
Remove the fuel line from that carb. Squeeze the primer bulb. If fuel does not come out, then you may have found your problem. If fuel does come out, then the problem could be inside the carburetor itself.
Disassemble the carb and remove the float, needle and seat. Then reassemble the carb. I know this is unorthodox, but this is my method. Put the fuel line back onto the carb. Prime the bulb and watch if fuel comes out the tiny holes in the top of throat in the carburetor. These tiny holes are the ends of the idle and low speed circuits. Also watch that fuel comes out the copper tube in the bottom of the carb throat. Be careful when you prime the bulb because excess fuel may also squirt out of an overflow hole in the top of the carb. If fuel comes out of the tiny holes in the top of the carb throat, and out of the tube in the bottom of the carb throat, then your problem is not fuel starvation. If fuel does not come out of all of these holes, then you have blocked jets and/or passages in the carb. In this case, remove all plastic and rubber parts of the carb and completely submerge it in a bath of Techron for 2 days. Then clean it with spray carb cleaner, reassemble and reinstall it.
Another possibility is that the top carb may have been flooding, preventing the top cylinder from firing. I don't think this is likely because a flooded motor typically will not start at all. If it were flooded, you would likely see some fuel leaking out of that spark plug hole unless you did the test where you removed the spark plug a day later, letting the fuel evaporate away. If the top carb is flooding the motor, you'll be able to see this while priming the bulb and looking into the carb throats. Once the primer bulb gets hard, you should still be able to pump it without any fuel leakage into the carb throats. If instead you see fuel leaking into that carb while priming the bulb, then your needle valve is not seating properly. To fix this, diassemble the carb and adjust/replace the float, needle and seat. When the needle valve is working properly, you should be able to blow air into the fuel inlet on the carb when the carb is right side up, but you should not be able to blow air into it when the carb is upside down.
