Mercury tickover

[alapmac]

My mercury 75hp outboard runs fine but is very rough at tickover. when hot it tends to stall when mooring. Seems particularly poor in gear at tickover will not rev when going astern, lots of smoke. Have changed plugs but no change. Tickover in gear is 700rpm approx. Any ideas

 

[BarryH]

Could be either overfuelling, or ignition control box prob, not as expensive as it seems, but with the smoke that you get i would start at the carbs, check fuel air mix, also check that they are balanced as this is a common cause for rough idleing and reluctance to pick up revs, you dont say what model it is have you got an autolube/oil injection system as this could be squirting too much lube into the fuel which will cause plug fouling at low rpm.

Thats enough to be going on with, if all else fails, give someone loads of money to sort it for you. Get the Seloc manual for your motor, its a good idiots guide and half the price of the official one.