Small Engines (Lawn Mowers, etc.): crusader marine engine, crusader marine engine, screw adjustment

Question
hi marc, i have a boat with twin crusader ch270 engines...the hull is 1978 and i assume the engines are original...i have the smell of gasoline coming from the exhaust/tail pipe of the starboard engine, and while at idle can see a slick of unburned fuel in the water around "tail pipe"....i replaced the fuel pump and that helped but didnt eliminate the problem....additionally, both engines bog above 2000rpm...no power, rpm's fluxuate...ive cleaned the flame arrestors and carbs on both engines and they still bog down above 2000rpm...

Answer
To address your first problem, if one engine is running excessively rich, the carb could be the issue (dirt, float height too high), idle mixture screw adjustment if it's way out (should start at 1 1/2 turns out from lightly seated) or a problem with the ignition.  If both engines lose power above 2000rpm and draw fuel from the same source, there could be a problem with the pickup / screen filter in the fuel tank.  Another issue could be with the vent for the fuel tank being plugged.  I am assuming you only have one tank.  If you have twin tanks, you need to see if you can correct the problem by switching to the alternate tank.  However, I recommend you go over the entire fuel system from tank vent to carbs (lines, filters, pumps, etc).  Do not take any shortcuts because being stuck out in the middle of nowhere with a dead boat is potentially dangerous.  Also, be very careful working with fuel inside the boat and make sure you run the blower to thoroughly exhaust any fumes before attempting to start the engine(s).  Hope this helps.