White smoke in outboard...

[Misfitts]

Hello everyone,
Last week My outboard (mercury 3.5hp) was running a little rough. I thought I got some bad gas. I mentioned it to my friend who after I stepped away, poured a full bottle of Lucas fuel treatment in the fuel tank (oily injector cleaner type stuff). Since then the outboard has been running rough and will bog down. When I try to accelerate, a bunch of white smoke appears as if is having a hard time burning the fuel. It eventually clears, but after I try to accelerate again, it could reappear. The smoke doesn't have a hot water smell, it smells more like oil burn off.

Obviously my friend feels bad, however, I'm not sure if the treatment did something or if this is simply burning off the oil-based fuel treatment even though I've cleaned the carb and flushed the tank.

Any advice would be appreciated

[Kettlewell]

First dump out all the gas and try a fresh tank. With those small outboards it is usually crud plugging the small jets in the carb and/or the float or needle valve sticking, and/or a dirty spark plug. With any fuel treatment only use the correct amount of products designed for gasoline engines. Personally, I run Stabil 360 in every load of gas that goes into my outboard and it helps prevent carb problems.

[Misfitts]

Originally Posted by Kettlewell

First dump out all the gas and try a fresh tank. With those small outboards it is usually crud plugging the small jets in the carb and/or the float or needle valve sticking, and/or a dirty spark plug. With any fuel treatment only use the correct amount of products designed for gasoline engines. Personally, I run Stabil 360 in every load of gas that goes into my outboard and it helps prevent carb problems.

I've gone through, cleaned the original carb, and now put a new one on. I haven't *flushed* the tank out, but may try that with a can of seafoam to give t a good rinse.

[Misfitts]

Originally Posted by Kettlewell

First dump out all the gas and try a fresh tank. With those small outboards it is usually crud plugging the small jets in the carb and/or the float or needle valve sticking, and/or a dirty spark plug. With any fuel treatment only use the correct amount of products designed for gasoline engines. Personally, I run Stabil 360 in every load of gas that goes into my outboard and it helps prevent carb problems.

I've gone through, cleaned the original carb, and now put a new one on. I haven't *flushed* the tank out, but may try that with a can of seafoam to give t a good rinse.

[MicHughV]

I've taken those little carbs apart. Here's the thing, Somewhere on the carb will be a matchstick size fine mesh filter screen. They are hard to spot, especially when gummed up, usually the case when using ethanol laced fuel.
Nonetheless, soaking the carb, etc, will not do much good, unless that filter is removed and cleaned. To remove the filter requires a small pin wedged around the edge.

Failing that, you can find new carbs on Amazon for very few $$$ and just replace the whole thing.

[Misfitts]

Originally Posted by MicHughV

I've taken those little carbs apart. Here's the thing, Somewhere on the carb will be a matchstick size fine mesh filter screen. They are hard to spot, especially when gummed up, usually the case when using ethanol laced fuel.
Nonetheless, soaking the carb, etc, will not do much good, unless that filter is removed and cleaned. To remove the filter requires a small pin wedged around the edge.

Failing that, you can find new carbs on Amazon for very few $$$ and just replace the whole thing.

Thanks - I actually just put a new card on it tonight and the behavior didn't change. Still bogging and blowing a white smoke. Doesn't smell steamy and there is a steady stream of water coming out....so I'm perplexed.

[MicHughV]

Well, I'm stumped then....perplexed as you say.

Lotsa gearheads on this forum, hopefully someone can provide an answer.
Presume the engine is a 4 stroke, so fuel is entering thru' an open valve.
White smoke would seem to indicate steam, a gasket leak ???