I have been searching and reading posts for days looking for an answer to my problems. I recently purchased a '74 Evinrude 6 HP outboard that is in very nice, clean condition. It appears to have been stored for most of its life and never been used in salt water. The previous owner had the engine serviced just before selling and it had not been in the water yet. I have verified that the carburetor was rebuilt and the igntion parts/points replaced. The fuel pump and lines are new as well. This work was all done by a reputable shop. I purchased a new fuel tank and hose.
The problem I am having is the engine fouls a new set of spark plugs in about 10 minutes when running WOT under load. It happens even more quickly if I start and stop the engine (2 or 3 starts and it won't rev above an idle and will eventually die). The fouling causes the engine to slowly loose power until it finally dies and won't restart. I have pulled the carburetor and opened it up looking for something that would cause a rich mixture. Everything looks good, the gaskets are in perfect shape, the passages are clean and there is no sediment or other contaminants in the carburetor of any kind. The float is set correctly and the fuel valve and seat are clean and undamaged. The idle mixture is adjustable but the WOT is a fixed jet. From what I can tell there are no missing parts or gaskets.
I started out with the Champion plugs installed by the service shop and have switched to a set of Bosch plugs from NAPA. I have tried gapping the plugs at .030, .025 and .020 with no real difference. I can clean the plugs and the engine runs fine for a short time. The engine will surge and stumble at WOT when under load even when it has clean plugs and there is quite a bit more smoke than I am used to seeing with an outboard. I am running fresh gas and using a quality but non-synthetic 2 cycle oil mixed 50:1.
The fuel consumption seems excessive which leads me to believe that I am running really rich. The plugs are heavily fouled, black and oily. I have considered rebuilding the carb again and replacing the igntion parts just to see if it made a difference but I have trouble believing there is much that would be changed with a few new gaskets. Since both plugs are similarly fouled, I am guessing that is unlikely that both cylinders have a weak ignition. The other thing I considered was changing out the thermostat. The engine seems to warm up and the water coming out of the cooling port is warm to the touch. I don't know if it should be hot and possibly this is my problem.
The engine starts very easily and idles well. I should mention that the choke is operating correctly and fully open when I am having this issue. This problem is driving me nuts. Let me know what you think and if there is any information you need to help me troubleshoot this issue.
Thanks in advance.
The problem I am having is the engine fouls a new set of spark plugs in about 10 minutes when running WOT under load. It happens even more quickly if I start and stop the engine (2 or 3 starts and it won't rev above an idle and will eventually die). The fouling causes the engine to slowly loose power until it finally dies and won't restart. I have pulled the carburetor and opened it up looking for something that would cause a rich mixture. Everything looks good, the gaskets are in perfect shape, the passages are clean and there is no sediment or other contaminants in the carburetor of any kind. The float is set correctly and the fuel valve and seat are clean and undamaged. The idle mixture is adjustable but the WOT is a fixed jet. From what I can tell there are no missing parts or gaskets.
I started out with the Champion plugs installed by the service shop and have switched to a set of Bosch plugs from NAPA. I have tried gapping the plugs at .030, .025 and .020 with no real difference. I can clean the plugs and the engine runs fine for a short time. The engine will surge and stumble at WOT when under load even when it has clean plugs and there is quite a bit more smoke than I am used to seeing with an outboard. I am running fresh gas and using a quality but non-synthetic 2 cycle oil mixed 50:1.
The fuel consumption seems excessive which leads me to believe that I am running really rich. The plugs are heavily fouled, black and oily. I have considered rebuilding the carb again and replacing the igntion parts just to see if it made a difference but I have trouble believing there is much that would be changed with a few new gaskets. Since both plugs are similarly fouled, I am guessing that is unlikely that both cylinders have a weak ignition. The other thing I considered was changing out the thermostat. The engine seems to warm up and the water coming out of the cooling port is warm to the touch. I don't know if it should be hot and possibly this is my problem.
The engine starts very easily and idles well. I should mention that the choke is operating correctly and fully open when I am having this issue. This problem is driving me nuts. Let me know what you think and if there is any information you need to help me troubleshoot this issue.
Thanks in advance.
