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Yamaha 200hp 2stroke. (200FETO 6G6 X 507697 U)
Problem - the Alarm for high temp sounds at about 3300rpm after 5 min running time and the engine cuts back on RPM. couple minutes in idle and were away again, this will repeat all day long. If I run the boat on lower RPM does not set the alarm off. If i run much faster the the time between alarms is much shorter. No indicator on the gauge when the alarm goes!! I have tested this by shorting the wiring at the motor and the beeper goes but no indication on the gauge. Im picking the "thermometer" on the gauge is for the Temperature sensor on the engine, not the switches near the thermostats
I have taken off the on/off switches on both heads and tested on a stove, both the switches operate same, trip at 87Deg and reset at 75Deg.
I have taken the temperate sensor off and tested that in cold water through to hot water and that too is working to the spec in the repair manual.
I have changed both the Thermostats 2 months ago and the water pump impellor. still had problems so i took it to a marine shop who also swapped the water pump housing. but it does not change the way the temp alarm operates.
I did a compression check and it did not indicate an obvious problem. The mechanic did indicate that the bottom crankcase seal is staring to pass as some fuel was running down the shaft. but nothing that should set off the temp alarm.
I also tested the level switches in the small oil tank on the motor and the larger tank on the boat. these worked fine too. Im thinking a blockage in the water system somewhere? or a gasket problem that becomes a problem at higher RPM?
Carbs were cleaned couple weeks back by the mechanic too, and spark plugs.
Im a bit stuck, the local mechanics have a very high rate and i would rather fault find myself and let them repair the problems rather than spending lots of time trying to find the problem.
Problem - the Alarm for high temp sounds at about 3300rpm after 5 min running time and the engine cuts back on RPM. couple minutes in idle and were away again, this will repeat all day long. If I run the boat on lower RPM does not set the alarm off. If i run much faster the the time between alarms is much shorter. No indicator on the gauge when the alarm goes!! I have tested this by shorting the wiring at the motor and the beeper goes but no indication on the gauge. Im picking the "thermometer" on the gauge is for the Temperature sensor on the engine, not the switches near the thermostats
I have taken off the on/off switches on both heads and tested on a stove, both the switches operate same, trip at 87Deg and reset at 75Deg.
I have taken the temperate sensor off and tested that in cold water through to hot water and that too is working to the spec in the repair manual.
I have changed both the Thermostats 2 months ago and the water pump impellor. still had problems so i took it to a marine shop who also swapped the water pump housing. but it does not change the way the temp alarm operates.
I did a compression check and it did not indicate an obvious problem. The mechanic did indicate that the bottom crankcase seal is staring to pass as some fuel was running down the shaft. but nothing that should set off the temp alarm.
I also tested the level switches in the small oil tank on the motor and the larger tank on the boat. these worked fine too. Im thinking a blockage in the water system somewhere? or a gasket problem that becomes a problem at higher RPM?
Carbs were cleaned couple weeks back by the mechanic too, and spark plugs.
Im a bit stuck, the local mechanics have a very high rate and i would rather fault find myself and let them repair the problems rather than spending lots of time trying to find the problem.
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