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99 yamaha ox66 power loss, idle cut off
i have a 1999 yamaha vmax ox66 200 hp, on a 20 ft bass boat.
new boat to me, used 6 times in the last month, all time ran superd top end at 73 mph, that last time i took it out seven days after the run prior, when cranked and let idle the engine cut off, its idlesfine and smooth than idles lower and lower till it will shut off, so than i attempted to run it. i cruised at 40 mph, with not problems at all once i brought the speed up and attempted to max the engine stopped in mid run, did not cut off just loss power completly, so i checked everything, attempted to run it again, this time when the power cut out i did not let off the throttle and the motor cought itself and tried to run but shut down again. so i just ran it back in at 40 mph with not problem. and if i let it idle still does the same thing cuts off after about three minutes. ok here is what i have done since the problem occured.
i have replaced all spark plugs, i have used both tanks to see if its a fuel tank problem, i have drained gas out of tanks to see if there is any water mixture, i have checked all the lines and there are no problems, i have taken the fuel filter that is in the plastic tube and it appeared fine, i have taken off the other fuel filter in the metal housing and cleaned that filter which was dirty (i only cleaned the bottom round filter i did not know there was a smaller one in that unit until reading these forums), i have idled the motor and when close to cut off i have mashed the plumb bob and there is no difference, i have also pressed the choke and there is no difference, and lastly i checked the 02 sensor, it was very dirty, the housing it was in i could turn it sideways and the exhaust byproduct actually poured out, the little rod between that and the block i pulled out and it was gunked up and was the diameter of a thread and i cleaned it back to toothpick diameter, i attempted to clean the 02 sensor and it appears ok.
sorry so long, any help greatly appreciated im new in my area and also broke haha so im attempting to avoid a mechanic
new boat to me, used 6 times in the last month, all time ran superd top end at 73 mph, that last time i took it out seven days after the run prior, when cranked and let idle the engine cut off, its idlesfine and smooth than idles lower and lower till it will shut off, so than i attempted to run it. i cruised at 40 mph, with not problems at all once i brought the speed up and attempted to max the engine stopped in mid run, did not cut off just loss power completly, so i checked everything, attempted to run it again, this time when the power cut out i did not let off the throttle and the motor cought itself and tried to run but shut down again. so i just ran it back in at 40 mph with not problem. and if i let it idle still does the same thing cuts off after about three minutes. ok here is what i have done since the problem occured.
i have replaced all spark plugs, i have used both tanks to see if its a fuel tank problem, i have drained gas out of tanks to see if there is any water mixture, i have checked all the lines and there are no problems, i have taken the fuel filter that is in the plastic tube and it appeared fine, i have taken off the other fuel filter in the metal housing and cleaned that filter which was dirty (i only cleaned the bottom round filter i did not know there was a smaller one in that unit until reading these forums), i have idled the motor and when close to cut off i have mashed the plumb bob and there is no difference, i have also pressed the choke and there is no difference, and lastly i checked the 02 sensor, it was very dirty, the housing it was in i could turn it sideways and the exhaust byproduct actually poured out, the little rod between that and the block i pulled out and it was gunked up and was the diameter of a thread and i cleaned it back to toothpick diameter, i attempted to clean the 02 sensor and it appears ok.
sorry so long, any help greatly appreciated im new in my area and also broke haha so im attempting to avoid a mechanic
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