Need Help! Power Loss after warming up

[JLB4757]

I have a 83 Murcury 50Hp 2 stroke that runs at 5500 rpm's when I first start the motor cold. Boat runs 25mph at 5500rpm. It appears to run good when first powered up. I will fish for several hours then when I start boat to head to a new location, I loose power. Now I am at 4000 rpm's, if I bring back to idle and re power, now I am getting 3000 rpms. The more I try an power down then power up I loose RPM's. Also, it appears to Idle much faster when this problem occurs. Any help would be appreciated... JB

 

[CharlieB]

Re: Need Help! Power Loss after warming up

Many engines will begin to idle fast as they begin to OVERHEAT, and start loosing top end power.

IMMEDIATELY check your water pump and thermostat.

 

[JLB4757]

Re: Need Help! Power Loss after warming up

Water appears to be circulating out the pee hole fine and visually don't appear to be restricted. Not sure if I have an overheat alarm or not on this older motor. Thanks... JB

I had been thinking that it may be a fuel issue, but I will take this into consideration.