72 65hp - engine goes flat with no power as if being choked

[kwizz]

Hi, Been out for a fantastic run with boat down beach. The boat and engine ran great after a while I returned back to shore to see friends, 5 mins later had loads of trouble starting engine, took the hood off and blipped throttle when turning over and fired up fine. My g/f jumped in boat and off we set had a short run about but noticed the engine losing power so swung around and headed for shore , now the engine was flat just ran at one speed if I give it loads of throttle an alarm would sound. The engine limped all the way back to shore quite a distance to be honest as i thought the engine was about to totally die but didn't and never cut out, seemed to be choking it's self.
Got back home put the engine on muffs and it fired up fine gave it WOT and no prob's.

Is this problem anything to do with a hot start type choke?

 

[ezeke]

Re: 72 65hp - engine goes flat with no power as if being choked

The only alarm on your engine is an overheat alarm. If the engine overheats it can bind.

You have probably blown a head gasket, so check your compression.

 

[kwizz]

Re: 72 65hp - engine goes flat with no power as if being choked

Done a compression test from cold and 15 min warm up.

Cold test gave 152-155 psi across the three

warm test gave top 152, middle 152, bottom 148.

Also before I started compression test I disconnected the thermo switch and jumped the terminals. On a previous post I read some time back I read a problem a guy had which was similar to mine and someone suggested removing the thermo switch. With the compression test results it seems all is fine within the engine.
With what I mentioned earlier about the alarm sounding, It was a bit strange, the engine seemed to be being controlled somehow like in a safe mode which I don't think it has for it's age, but the throttle stayed constant and when applying more the engine sound or power wouldn't change it was only when I gave it WOT that a little alarm would sound for a second, but the engine still didn't change. Yet the motor still chugged on like being choked without stalling and got us back to shore, and when I took the hood off the engine it was only mildly warm all around. I'm wondering if water or dampness has got in somewhere and caused this?

Hopefully the weather is dry over the weekend and all be it totally freezing I can have another test run.