Re: Tohatsu 5hp Idle
These carbs are very sensitive to proper setup, and they don't tolerate particle impurities in the fuel. Have you done a thorough and proper soaking in carb cleaner? The spray stuff is not strong enough to dissolve varnishing in the difficult-to-access passages, especially the idle circuit. The emulsion tube with the small holes has very little to do with the idle circuit, but rather provides air/fuel blending for the power side of things. You would be advised not to increase the size of the holes in the emulsion tube, as that will throw the mixture way off. Don't even use a wire to clean them, as that will dramatically affect how the fuel flows through them, causing weird turbulence and other difficult-to-tune conditions.
You should not be getting any water in the fuel at all. If you are finding water in the carb, I recommend using a Baja-type filter funnel for filling the tank -- I assume that is what you are using. But.. with a fast-flowing station pump, it's possible that the fuel is so mixed up that impurities have trouble getting separated. I have had a fleet customer with several copies of this motor who stopped having water issues when he started using the filter funnel. He fills a jerry can at the pump, and then transfers the fuel to his OB tanks with a steady, non-turbulent pour the next day. If the boat can reasonably accept one, you could also use an in-the-gas-line 10-micron water-separating filter to help, but... if E-10 gas has water in the bottom of the tank, it's already pretty poor fuel, because it has suffered phase separation. There is no way for a consumer to fix phase-separated E-10. If that's what's happening, see if you can get non-ethanol fuel from a marina or farmer's supply station. Here in NY, we can buy it, but it has to be designated "off-highway-use" fuel, and costs more than E-10.
