Hi all,
I have a 1980 belgium built mercury 50 2 stroke 4 cylinder outboard s/n 9283020. I've had it 2 years and it's never started or idled very well, but ok when WOT. Last year I decided to bite the bullet and strip it down. I removed the power head (I had to use 2 x 3 tonne car jacks to prize the lower unit off) and took of the cylinder head to replace the oil seals as I saw signs of water in no.4 cylinder. I also had to replace the exhaust manifold baffle plate as it was badly corroded. At the same time I de-coked the exhaust ports and removed all the limescale and replaced the water pump. After putting it all back together I cleaned the carbs in an ultrasonic bath, replaced the needles and the gaskets that fit between them and the power head. I didn't replace the fuel pump gasket or diaphrams as they looked ok and I have no reason to think they are faulty. However, after all this I am still having similar problems. I have set up the idle mixture screws to about 1.5 turns out on each carb and it idles quite nicely now, but when I throttle up it looses power momentarily which sugests a sync and link problem. The wierd thing is that it only does it on the 3 & 4 cyls (I pulled the plugs on 1 and 2, then on 3 and 4), It throttles up nicely when running on 1 and 2. Does anyone have any ideas?
I have a 1980 belgium built mercury 50 2 stroke 4 cylinder outboard s/n 9283020. I've had it 2 years and it's never started or idled very well, but ok when WOT. Last year I decided to bite the bullet and strip it down. I removed the power head (I had to use 2 x 3 tonne car jacks to prize the lower unit off) and took of the cylinder head to replace the oil seals as I saw signs of water in no.4 cylinder. I also had to replace the exhaust manifold baffle plate as it was badly corroded. At the same time I de-coked the exhaust ports and removed all the limescale and replaced the water pump. After putting it all back together I cleaned the carbs in an ultrasonic bath, replaced the needles and the gaskets that fit between them and the power head. I didn't replace the fuel pump gasket or diaphrams as they looked ok and I have no reason to think they are faulty. However, after all this I am still having similar problems. I have set up the idle mixture screws to about 1.5 turns out on each carb and it idles quite nicely now, but when I throttle up it looses power momentarily which sugests a sync and link problem. The wierd thing is that it only does it on the 3 & 4 cyls (I pulled the plugs on 1 and 2, then on 3 and 4), It throttles up nicely when running on 1 and 2. Does anyone have any ideas?