Despite my best efforts (including those efforts derived from the valuable suggestions here), my motor seems to get 'tired' after motoring for more than 4-5 hours. It runs at 2000 RPM steadily, and the first four hours it sounds completely steady and strong. Then, it slowly exhibits hesitation, which gradually increases until everyone on the boat is certain the engine is going to die. But it never does. In fact, it never goes below 2000 RPM!
Here is everything I've tried to resolve the issue:
1) Verified there are NO leaks in the fuel line. I even installed a priming bulb between the tank and the primary fuel filter, and when I pressurize the system, no leaks occur anywhere in the fuel line (although fuel does spill out of the carburator when I pump the priming bulb hard, but this does not surprise me).
2) Replaced the epoxy filled coil with a brand-new oil-filled coil bought from Don
3) Cleaned every electrical connection on engine and at panel, and sprayed each with anti-corrosion spray.
4) Checked and verified all of the following are in order: Temperature 140- degrees and Oil Pressure 40psi steady throughout motoring, Timing (via RPM optimization at warmed-up cruising speed) AND spark on all four plugs, Compression (90PSI in all four), Carburator (thorough cleaning of all jets), Plugs (dry and grey after several hours of use).
I have the crankcase ventilation kit and adjustable carb, both bought from Moyer Marine. Carb is set to exactly 1.5 turns from closed, and one thing I do notice every time I clean the carb is that the flame arrestor/throat area that feeds the scavenge tube usually has an oily, blackish gas mix in it. I think this is fairly normal though, but wonder if my gas mix could be too rich (or too lean??).
I'm stumped. Why would it motor fine for several hours, and then start to hesitate? When I start it back up (after it has cooled, it runs fine for at least 4 hours, and then repeats with the hesitation). Any help would be greatly appreciated.
Thanks in advance.
Here is everything I've tried to resolve the issue:
1) Verified there are NO leaks in the fuel line. I even installed a priming bulb between the tank and the primary fuel filter, and when I pressurize the system, no leaks occur anywhere in the fuel line (although fuel does spill out of the carburator when I pump the priming bulb hard, but this does not surprise me).
2) Replaced the epoxy filled coil with a brand-new oil-filled coil bought from Don
3) Cleaned every electrical connection on engine and at panel, and sprayed each with anti-corrosion spray.
4) Checked and verified all of the following are in order: Temperature 140- degrees and Oil Pressure 40psi steady throughout motoring, Timing (via RPM optimization at warmed-up cruising speed) AND spark on all four plugs, Compression (90PSI in all four), Carburator (thorough cleaning of all jets), Plugs (dry and grey after several hours of use).
I have the crankcase ventilation kit and adjustable carb, both bought from Moyer Marine. Carb is set to exactly 1.5 turns from closed, and one thing I do notice every time I clean the carb is that the flame arrestor/throat area that feeds the scavenge tube usually has an oily, blackish gas mix in it. I think this is fairly normal though, but wonder if my gas mix could be too rich (or too lean??).
I'm stumped. Why would it motor fine for several hours, and then start to hesitate? When I start it back up (after it has cooled, it runs fine for at least 4 hours, and then repeats with the hesitation). Any help would be greatly appreciated.
Thanks in advance.
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