OK, 1987 30 yamaha 2 stroke, 3 cyl. oil injected, elec start. sat for 10 years (winterized i think). i'm orig owner, low hours, always flushed after use. decided to use it this year. changed impeller. new gear oil. rebuilt carbs.new gas tank , old gas hose. ran great first little ride, ran about 15 minutes perfectly. 2 weeks later went for a ride, not quite as good, rough idle. 2 more weeks another quick ride, worse yet. barely made it back to dock. got home replaced fuel connection at motor (was pissing and i guess sucking air). took fuel pump apart , diaphram looked ok but replaced it anyway. the fuel pump gasket had a tear in it. replaced it.
4th litte ride , no idle at all, was able to get from dock (barely, feathering choke and throttle) barely able to get planed off (13' whaler) , once planed felt like it could go forever, very smooth, but very lttle power , like half trottle although throttle was pegged.
plan : check compression, if it's good, clean EVERYTHING again. check spark.
i'm thinking the gasket and diaphram were dry-rotted and small pieces were breaking off those first few rides. blocking the jets. when i remove the fuel lines at the top and bottom carbs and pump the ball, plenty of gas flows.
how does the fuel pump use the stroke of the motor to pump? there is no hose , it must work thru the middle carb.
any help is apreciated. i've read so many posts with similar problems but they all just END. doesn't seem like anyone posts the SOLUTIONS. I WILL FOR SURE .
sounds like you fed debris back into the carbs, strip them and clean them agan.
lots of varniish has adhered to the fuellines and todays fuel will clean them and pass the debris to the carbs.
well, carbs rebuit again, new gasket and diaphram in fuel pump, new gas. still low compression in middle cylinder.
before i try to fire it up (and do a decarb, it's never been done). i decided to check spark today. looks like only middle cylinder has spark. any ideas?. will double check tonight when it's dark, maybe it's just weak in cylinders 1 and 3.
if no spark tonight, i'll try swapping coil packs and plugs around to narrow suspect parts and go from there. this motor is oil injected, i'm assuming it's ok to crank without fuel connected, right ?
yamaha 30 no idle tried ALMOST everything
Linear Mode
