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Yamaha 150 Overheat alarm goes off randomly
I have twin 1996 S & L 150 txru's. The overheat alarm on the stbd engine goes off randomly and drops the rpms. I have replaced the waterpumps, thermo switches and thermostats in the last two weeks. I have temp gun and port engine will be at 120 and stbd engine will be about 130 when the alarm goes off after running 10-15 minutes at 4000 rpms. Stbd gauge arrow points to the overheat symbol. Alarm sound is not steady or even intermittent, sort of like a warble before it finally goes full steady sound. It will happen when I first start off, after making a hard turn or whenever, no rhyme or reason.
Main power wires to the engine were replaced last season after a meltdown within the tube running to the outboards. Positive wire melted through the insulation to the ground wire.
I am thinking it is electrical, so I have checked the wiring connection at the back of the ignition plate and all seems clean and tight. Could that key switch assembly be the culprit? I also load tested both batteries and both checked out fine.
This problem has not come up suddenly, but been gradually getting worse over last season.
Main power wires to the engine were replaced last season after a meltdown within the tube running to the outboards. Positive wire melted through the insulation to the ground wire.
I am thinking it is electrical, so I have checked the wiring connection at the back of the ignition plate and all seems clean and tight. Could that key switch assembly be the culprit? I also load tested both batteries and both checked out fine.
This problem has not come up suddenly, but been gradually getting worse over last season.
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