Home › Forum › Ask A Member › 56 Evinrude 30 hp › Reply To: 56 Evinrude 30 hp
Well, it could be most anything. Could be something as simple as improper carb/ignition sycronization. Some of these engines had the “economizer linkage” (not sure if this one has it though). If that feature is misadjusted, the carb might open way too early causing it to run lean. Just because the carb “looked clean” doesn’t mean it is working properly.
The engine may be losing spark on one cylinder, or have erratic ignition at lower RPMs as well. That feature you mention with the hose is the ignition system vacuum switch that prevents the engine RPM from running away when you cut the throttle back quickly. This could be malfunctioning causing the engine to lose spark on one cylinder when the throttle is cut back.
The biggest thing here is to determine whether the ignition or fuel system is causing a problem. Any way you can post a video of the engine misbehaving? I realize it won’t post hear because the file is too large, but maybe you can post it on youtube. You can even send it to me through email if you like.
Finally, I realize the past owner had rejuvinated this engine, but it is possible that is has poor compression, or perhaps water leaking into one/both cylinders. It only takes a few minutes to check compression and doesn’t cost anything to check.