Originally Posted by ollyit
thanks I'll check the prop -
thanks for your time guys I took it out gently, its a bit more noisy now, my marine engineer friend assured me it wasnt the main bearing as he'd be able to hear it, I took it out and it was okay, hit "wot" a couple of times, just about managed to get back tot he slipway - it lost at least 50% power, and limped back around 10knots - lucky I wasnt to far out, it would bog down if I throttled up so I pulled back, does this sound like fuel to you?
thanks in advance
I had similiar problem with a Yamaha 60, it was in fact fuel pump.
Loss of Power is due to:
1. Not proper combustion
2. Mechanical failure in your gearbox
So to check the first one, do the following;
Does it smoke more? Does it smell of unburnt petrol? Check the cylinder compression (buy a tester from Halfords for like £30, you will use it alot) if the compression test was OK, then check the spark plugs, if the bottom cylinder plug was WET then it is probably fuel pump diaphragm.
Mechanical failure can be identified easily as your engine under load may sound differently than neutral position.
My 2001 Yamaha failed on Gearbox so I am after a new engine now...!