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Overheating

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wallymaster

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"I have a Mariner 9.9 (198

"I have a Mariner 9.9 (1981). Starts and idles excellent, but when accelerate to full throttle, will go full speed for maybe 20 seconds, then slows down to about 70% power and remains there. Problem especially apparent when there is a heavier load in the boat. I have replaced fuel pump, fuel filter, carb cleaned, new fuel tank/hoses/connectors. I think (?) the problem may be an overheating issue: the telltale has a solid stream, but there is only a small mist coming out of the exhaust relief hole in the leg at full speed. My other motors have lots of water coming out that exhaust hole at full speed. Shouldn't there be more than just drips and mist coming out that hole at full throttle? Could it not be getting proper cooling due to blockage? Though the telltale indicates the pump is good, is it necessarily an indicator taht there is good cooling? Any other thoughts on this problem?"
 
"Some engines spray more than

"Some engines spray more than others out the relief hole, it also depends on how low in the water it sits. Sounds like your sucking air in the fuel system from a loose clamp or cracked line. Have you tried pumping the fuel bulb to see if the problem goes away?"
 
"Yes, pumped the bulb and does

"Yes, pumped the bulb and doesn't help. Bulb is hard, and all fuel lines/ connectors and the fuel pump have been replaced."
 
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