I found the solution here in these forums, so decided to post my problem as well. I was having problems with hard starts, no starts, engine miss, and smokey exhaust when running, etc. After reading about the similar problems with Tohotsu and Nissan carbed motors with what some called "making oil" , I investigated the crankcase issue and found mine to be full of gas and oil to the point where the dipstick practially popped out under pressure when I pulled on it. Apparently this is a common and known problem with some models of Tohatsu, Nissan, and Honda.
It appears that the reasons for this in my cas might be a lot of idling through canals to get to larger lakes in my area, and more than likely a fuel tank that was not properly vented for my motor. About a year ago, my original 6 gallon Atwood portable fuel tank was stolen and I replaced it with a similar tank from iboats here in central Floorida. I find out now that these tanks come with a cap that is only vented while the engine is running. This is due to the recent EPA law that dis-allows automatic venting gas fumes to the atmosphere. I had never bothered with disconnecting the fuel line at the dock as my original fuel tank had a manually vent cap. The cap on the new tanks have a knurled vent screw, but only vents the tank when that knurled scree is open and depressed. At the dock the sun expands the fumes in the tank, and in my opinion, pushes raw gas past the carb floats, and finds it's way to the crankcase and on top of the pistons at times.
I did a thorough drain and flush of the engine yesterday, replaced the crankcase contaminated oil and serviced the lower unit. The engine runs smooth as a top, with no hesitation in starting or acceleration. At present I am running the cap loosened to prevent the pressure build up, until I can replace it with an original vented cap.
In my opinion, the retailers of these new tanks with non auto vented caps should certainly question the purchaser of it's use and advise them at the time of sale of the potential problems discussed here. At the very least, the manufacturer should attach a tag with a warning discussing this potential problem or a warning molded right in the tank. If I had not found the invaluable info on these forums, I may have been out several thousand dollars in repair bills from marine repair shops that may or not know of this problem. My inital assesment was that I had a head gasket problem until I determined that the contaminant was gasoline instead of water. I believe I caught my problem in time to prevent major damage to the engine. I will closely monitor the engine for any future problems of this nature.
Good luck and I hope this info is helpful to others.
It appears that the reasons for this in my cas might be a lot of idling through canals to get to larger lakes in my area, and more than likely a fuel tank that was not properly vented for my motor. About a year ago, my original 6 gallon Atwood portable fuel tank was stolen and I replaced it with a similar tank from iboats here in central Floorida. I find out now that these tanks come with a cap that is only vented while the engine is running. This is due to the recent EPA law that dis-allows automatic venting gas fumes to the atmosphere. I had never bothered with disconnecting the fuel line at the dock as my original fuel tank had a manually vent cap. The cap on the new tanks have a knurled vent screw, but only vents the tank when that knurled scree is open and depressed. At the dock the sun expands the fumes in the tank, and in my opinion, pushes raw gas past the carb floats, and finds it's way to the crankcase and on top of the pistons at times.
I did a thorough drain and flush of the engine yesterday, replaced the crankcase contaminated oil and serviced the lower unit. The engine runs smooth as a top, with no hesitation in starting or acceleration. At present I am running the cap loosened to prevent the pressure build up, until I can replace it with an original vented cap.
In my opinion, the retailers of these new tanks with non auto vented caps should certainly question the purchaser of it's use and advise them at the time of sale of the potential problems discussed here. At the very least, the manufacturer should attach a tag with a warning discussing this potential problem or a warning molded right in the tank. If I had not found the invaluable info on these forums, I may have been out several thousand dollars in repair bills from marine repair shops that may or not know of this problem. My inital assesment was that I had a head gasket problem until I determined that the contaminant was gasoline instead of water. I believe I caught my problem in time to prevent major damage to the engine. I will closely monitor the engine for any future problems of this nature.
Good luck and I hope this info is helpful to others.
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