My two stroke 30 hp has set up for two years with occasional cranks with water hose hooked up to keep carbs cleaned. I decided to clean boat and get it ready for a trip. Hooked up water and put fresh gas on and topped off oil reservoir . Pulled cord three or four times and she fired up . All sounded good for a couple minutes , then a bad rough rattle noise started coming from either the engine or the lower unit only when at idle . It would go away when I throttled up. I shut the engine off . Things I checked cleaned carbs , checked spark on all three cyl doesn't look strong but is sparking , lower unit had no oil in it so I put new oil looks like a small seal leak. Tried to crank and all I get is an occasional backfire out the prop exhaust. Never had this problem before, did the lower unit lock up and shear the key on the fly wheel and got the timing off ?
