Re: Tohatsu 18 hp 4 stroke auto chock problem
When I put this motor to bed last fall it was running great. So, two weeks ago when I hit the lake for a spring motor check out, it was very hard to start, and the idle was loaded up real bad, then smoother above idle, and then bad load up above half throttle. So I went after the carb. Went I tear down a carb, I take extreme care especially if it is a first time, which this one was. After find it in perfect condition and remounting it, just to find it with these same conditions, I pulled it down again on Saturday. This time I spent near two hour going through every port, channel, jet, and pin hole, which this carb as nearly 20. Everything open and clean. Remounted, and the same malfunctions. This is where you want to just throw it against the wall. I was checking the parts PDF and looking at the jet sizes to see if my boy had slipped in some big one as an early April fools joke, when I noticed a part called a rubber plug that is to cover the port to the idle jet. I knew I had not seen it on my carb's idle jet port, so I started a floor search of the shop work bench area. Eureka! Here was the small hat shaped plug. After reassembling it with the port plug, it ran smooth all the way from idle to WOT. This little plug must have fall out of the port over winter, and when I removed the bowl it slipped away before I seen it. I noticed on the parts list that all the 9.9, 15, and 18 hp carbs have this part, and probably others as well.