Mercury 800 troubles

[adice67]

I have a 80 hp mercury from the late 70's or 80's. Serial number 1890906. it has a red band around the cowl where the name is. Not for sure if this serial number matches what the power head is. i bought this used a few years back and has been running fine until recently. It is a straight 4 cylinder. It starts up fine and idles fine for the most part but it has not top end speed. It is smelling more like gas when running also. When I stop the motor it looks like a gas spill in the water. It doesn't sputter or complain at all just can't get up to the speed it used to and like I said the gas smell is horrible. Any thoughts what may be wrong?

 

[Faztbullet]

Re: Mercury 800 troubles

Check your compression 1st, the fuel system 2nd. You could have low compression on a cylinder but sounds more like fuel delivery system problem. You could have a fuel pump diaphram/s ruptured dumping excessive fuel into cylinder, fuel line leaking under cowling or a carb problem like needle & seat or float sinking causing a flooding problem. All these will cause a poor top end and a rainbow in water from unburnt fuel.....

 

[adice67]

Re: Mercury 800 troubles

Thanks. Checked the plugs and found one leaking fuel. It had teread repair done. When I pulled the plug the repair came out also. Looking to have it fixed and changing all the plugs. Hope it will fix the problem and run again.