I'd agree with the fuel system. The carbs can get gunked up so quick with sediment and varnished fuel its not even funny
. What year is your boat and engine
? That will determine what carb you have. Read up on how to properly clean and disassemble and reassemble these carbs and clean it all. You can't get it clean without removing it from the engine and tearing it down. A can of carb cleaner will not do the trick with the carb still assembled.
Once you get the carb cleaned up read up and pay attention the the proper adjustment procedures and get the carb and engine dialed in correctly. This will save on fouled plugs or running too lean and burning a valve.
Also if your boat doesn't already have it put an electronic ignition kit ($265 at Atomic 4 - Indigo Electronics, Inc.
) on it if you can afford it! I don't work for them just an awesome resource for all sorts of great updates to your engine. This will save you lots of fiddling with points and inconvenient break downs when they go bad... If you can't afford it no sweat just check the adjustment and condition on the points and test your capacitor. Then follow recommended maintenance
I have a 1961 boat that probably has a 1958 engine in it. After replacing the fuel filter
and "cleaning" the carb several times it still wouldn't idle quiet right. I realized that due to my cast steel
float bowl there was rusting happening in the bottom of the bowl. I scrapped and brushed until it was good and clean. I then went and cleaned every orifice and tube. It turns out the bottom of my idle tube was completely packed with rust sediment. It now idles smoothly and delivers plenty of power.
In short, like almost all engines, they are great and very reliable when properly maintained
and will last a very very long time.