" Joe,
Yah, that'
" Joe,
Yah, that's hesitation, I misread you on "surges", that's actually what it's called but I was thinking of something else. I don't get how it could be electrical as it seems to be running correctly at all other points other than that transitional period. It really sounds like fuel.
Just for kicks, try giving it a good decarb, use whatever brand of spray-in-carb stuff they sell for marine in your area. I have found that with my merc, every so often (depends how much low speed running I do, but about 20 hours usually) it will start hesitating and runs perfect after a decarb. Rarely do magic fixes like this actually work, but it's cheap and easy enough. After that, check the compression and be sure you are dealing with a good engine before wasting time diagnosing.
Checking spark is easy enough; be sure all cylinders are firing with strong spark.. doubt it's it, but proove to yourself that good spark is there. Just for kicks as well, pull the fuel line off where it feeds the carbs, pull the MOB switch to prevent ignition and pull off the spark plug leads to be safe; squeeze the primer bulb and observe smoothe easy flow through the line. Turn over the engine (hopefully this engine lets you do that with the MOB switch yanked); observe that the fuel pump is sending some sort of steady pulse to the carbs for a few seconds.
I'd look into fuel issues. Assuming you are SURE the carb's are clean; If that engine has an adjustable low speed jet, try opening (loosen screw, counter-clockwise) it up a little, say 1/8 of a turn, and if that doesn't work try another 1/8 etc.. If the engine runs like hell, with no increase in performance, put them back. Next thing I would suspect is something to do with syncronization; like the throttle is not correctly line up with the approximate RPM range and ignition. Pretty much perform the tune up procedure, Timing and Syncronization. I can't help you with that, but a repair manual will have it. Also, take a look at the plugs, that may give you a clue of what's happening. If it's running lean at that RPM, chances are it's running funny at others at well, regardless of performance. Hope this helps,
Jon "