My 1992 150 Fast Strike has about 900 hours on it, and has been ultra reliable. Over the past couple of seasons, the engine's hot idle speed has begun to wander. If I take the engine out of gear after making a run, the idle speed will start at about 1000 rpm, and perhaps drift up as high as 1200-1300 rpm. Shut it down, restart it a couple of minutes later, idle will start at normal (about 800 rpm), then begin drifting up again. Idle speed in gear is also a bit high, but remains steady. I know this engine has the automatic timing advance when it's cold, and that is also working properly. As soon as the engine begins to warm, that automatic timing advance "turns off", just as it should. Everything I've checked seems normal. I cannot detect any vacuum leaks, all the spark plugs look totally normal. The engine starts perfectly, even in the coldest days in Maine. Plus, the engine runs with plenty of power, just as it did when brand new. This is my first time on this forum, so I hope somebody out there has a clever idea or two. I'd be happy to suppy additional info. if needed. Thanks in advance.
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1992 150 Fast Strike Wandering Idle
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Could be worn throttle linkage or throttle plates in carbs but probably an air leak in intake or crankcase, spray engine block with silicone spray while it's running to find leak.
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Thanks for the tip. I've already checked the throttle linkage and carbs to no avail. I'm assuming the engine speed will change dramatically by spraying silicone lubricant. Based on your knowledge, do you suspect one area over another? This era engine has a few runs of small diameter rubber tubing, and I've wondered if the problem could be there somewhere. Any other thoughts?
Thanks again.
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