Originally Posted by pow2gran
Then had a blast up the Menai Straits at 5600rpm just going back when I lost power with the engine running no more than 3000rpm. Also the engine would not tick over without stopping. I had to start it with throttle on in neutral if it were cold. It then ran as if only firing on two cylinders. It isn't plugs as they were new today as I had the feeling of miss firing on last time out. Water is pumping OK
Any suggestions to cure the problem would be appreciated
Rule out the basics first. Were you using fresh fuel? Does the fuel go through an inline filter before going to the engine? (rule out water/fuel contamination). Was the tank properly vented?
When the engine revs drop - feel the fuel bulb - is it hard or soft? Could be fuel pump or diagraphm related.
Plenty oil in the oil reservoir? I know it doesn't use much oil.
Pull the spark plugs. I know they're new - but are the oily or any signs of carbon build-up?
When you've finished with the boat for the day - do you drain the remaining fuel in the carbs? I got into the habit of running the engine on muffs, then disconnect the fuel line so the remaining fuel is burnt off. I wouldn't have thought this is the problem, but a carbs may need cleaned?