Hi - longtime reader, first time poster....thanks in advance for any information anyone might have!<br /><br />Our boat has, for various reasons, been sitting at the dock for most of the last six weeks or so, during which time we've had a lot of very hot weather (weeks in the mid-90s). We've had it out twice in that time, once about three weeks ago, and then again today. <br /><br />Both times, the engine (1998 Honda 90 o/b, with 4 carburetors) started and idled fine, but then ran rough between about 1200 and 2000 RPM. Seemed fine at higher RPM, and never hesitated or failed to respond when asked to accelerate. Three weeks ago, the roughness was evident when we were setting out, but not on the way back (about an hour each way). Today we noticed the roughness when heading out, and also got a gasoline smell during the rough running so we went back in - but did check and make sure that the engine ran OK at higher RPM, right up to WOT. <br /><br />Back at the dock we took the cowl off and (literally) sniffed around inside; both my wife and I are pretty certain that the fuel odor was coming from the lowest of the four carbs. We tried revving the engine at the dock using the choke, and it ran fine - but the gas smell at the lowest carb was more evident after doing this. Also, on some of the surfaces near the lowest carb, there was a thin but detectable layer of sticky brown gunk.<br /><br />Any theories on what might be going on here? I notice in my service manual that there's a "mid-range circuit" in the carbs that sends fuel through bypass holes in the 1/8 - 3/8 throttle range, which is about where we're having the problem - could these holes be clogged? Someone else suggested that a carb float could be sticking open, causing that carb to overfill, which could cause the mixture to be too rich and excess gas to leak out.<br /><br />I was thinking of running some carb cleaner through the engine, at least as a first step, but I wonder if a full carb service is in my future....thanks in advance for your input!
