Mariner 150 mag III smoking excessively

[wargle70]

I have just bought a 1994 ProCraft 18' bass boat with a Mariner 150 Mag III. The oil injection has been removed sometime in the past. I have been mixing Quicksilver TWC-3 at 50:1 and the motor smokes really bad on start up and cold idle. I doubt if the motor has ever been de-carboned, which I plan to do. If I de-carbon the engine and switch to a full synthetic oil will that reduce the smoking? I know it will smoke some when cold, but it looks like a mosquito sprayer now till it warms up.

 

[Chris1956]

You need to remember that the gas in the carbs evaporates, leaving the oil behind. So you are burning a very oily mixture upon cold start. Will synthetic oil help? Maybe,,,I have found some that smoke less and some that don't. Even synthetic oil will smoke a bit upon cold start. It is the nature of the motor.....Get a Optimax, as that should not have that issue.

 

[enginepower]

What Chris said...nature of the beast. Only thing you can maybe check is make sure you don't have a leaking float needle flooding the engine when you kill it. Does it run ok at all ranges, idle and take off? Switching oils may help it some or may not. Extra oil is good for an engine on cold start!!!

 

[Faztbullet]

Also plugged recirculating check valves will cause this as fuel/oil puddles under reed block instead of being pulled into other cylinders and burnt off..

 

[wired247]

I use the premium plus Penzoil semi synthetic. $16 a gallon on sale. I've TRIED to make it smoke and I have failed and thats running up to 32:1.