2 Stroke Outboard - Excessive smoking?

[bigdog]

My V4 90 HP Johnson 2-stroke, (oil injected), seems to me to be excessively smoking? This is not a new symptom, as has been this was since I purchased last year.

The engine actually appears to be running smoothly at all RPM's, cruises w/o effort at 4000-42000 RPM. No hesitation at any speeds, and doesn't appear to be consuming lots of oil. Smoking being noticed while idling at dock.

My knowledge of 2 strokes, that display excessive smoking, my first thought would be the engine is running to 'rich'.

Can this be corrected my a simple carb. adjustments ? In my case this would be left to a marine tech, as I have 4 carbs. to be tweeked !

Last, if left unchecked, can running 'rich' cause other issues down the road?

Thanks for your feedback.

Bigdog

[chipj29]

Sounds like it is getting too much oil. The oil pump could be stuck open.
It isn't great for the engine, but I don't think it is catastrophic. You will foul a lot of spark plugs though.

I would get it checked out.

[Dave R]

They tend to smoke a lot when cold, it's normal. When warm, there should still be some, but not a lot. Assuming it;s not running cold, try different oil. XD-50 and XD-100 oils are known to be much less smokey than non- synthetic oils.

[bigdog]

Thanks DaveR for tip on diff oils XD50/100......

On that note, I'm using XD30 now, a non-synthetic oil, which the engine has apparently always been used.
Still have about 1/3 oil reservoir tank left of this oil.

Silly question, and think I know the answer, but have to ask......

Could I possibly mix XD50 synthetic with the XD30 'non synthetic' ?

Otherwise will wait to oil is almost completely exhausted before swapping out.

Thanks,
Bigdog

[Dave R]

Originally Posted by bigdog

Thanks DaveR for tip on diff oils XD50/100......

On that note, I'm using XD30 now, a non-synthetic oil, which the engine has apparently always been used.
Still have about 1/3 oil reservoir tank left of this oil.

Silly question, and think I know the answer, but have to ask......

Could I possibly mix XD50 synthetic with the XD30 'non synthetic' ?

Otherwise will wait to oil is almost completely exhausted before swapping out.

Thanks,
Bigdog

You can mix them with no issues. If it still smokes too much at idle, you'll probably want to address the oil injection pump. That said, I can't fathom how it would possibly add too much oil, it operates directly on engine intake pulses (so it can't possibly run too fast) and is a positive displacement pump, if memory serves. I suppose it might have a failed part inside, but I dunno The only failure I am aware of with them is when they stop pumping and you replace them. AFAIK, there are no rebuild kits for the oil side of the pump.

Here's a cutaway diagram of the VRO pump like you have:

[chipj29]

Originally Posted by Dave R

You can mix them with no issues. If it still smokes too much at idle, you'll probably want to address the oil injection pump. That said, I can't fathom how it would possibly add too much oil, it operates directly on engine intake pulses (so it can't possibly run too fast) and is a positive displacement pump, if memory serves. I suppose it might have a failed part inside, but I dunno The only failure I am aware of with them is when they stop pumping and you replace them. AFAIK, there are no rebuild kits for the oil side of the pump.

Here's a cutaway diagram of the VRO pump like you have:

I was always under the impression that when oil pumps fail, they fail "open", so there is no stoppage of oil flow to the motor. It results in extra oil, and extra smoke.

[Dave R]

Originally Posted by chipj29

I was always under the impression that when oil pumps fail, they fail "open", so there is no stoppage of oil flow to the motor. It results in extra oil, and extra smoke.

I have never taken one apart, so I don't know for sure.

Here's what I do know:

If the oil has to be pumped in, that means it's not under pressure and is relying on the pump to move the oil.

The pump has a piston that moves up and down and is powered by intake air pulses. The speed that it moves up and down is solely dependent on the engine speed. It cannot run too fast.

With a reciprocating pump, there has to be a pair of valves that: let oil in to the pump from the reservoir on the down stroke, and prevent oil from going back to the reservoir on the upstroke (valve 1) and let oil out toward the fuel on the upstroke, and prevent fuel/oil from coming back into the pump on the downstroke (valve 2). If either valve fails, the engine will get less oil.

The pump can vary the oil mixture ratio. This is a mechanism that I don't understand (and the picture is no help...). I can see where a failure here could indeed let too much oil into the engine.

[bigdog]

Just read on another boating forum (Iboats.com), similar excessive smoking with a 2 stroke, and feedback suggested a possible air leak or vacuum leak in the system will cause excessive oil consumption if you are using the VRO system.

Also indicated was fuel restriction or pump problem will cause it to dump more oil.

Does that make sense to anyone?

Just to ad more fuel (sorry couldn't resist), to the story and some background..... I'm using a auxiliary fuel tank, with the VRO oil tank connected.
Just had to have my under-deck fuel tank pumped, so been using aux. tank most of season.

Maybe the aux. tank and VRO is causing excessive oil dump into gas mix?
Just a guess !

Thoughts?

[Dave R]

Originally Posted by bigdog

Just read on another boating forum (Iboats.com), similar excessive smoking with a 2 stroke, and feedback suggested a possible air leak or vacuum leak in the system will cause excessive oil consumption if you are using the VRO system.

Also indicated was fuel restriction or pump problem will cause it to dump more oil.

Does that make sense to anyone?

Just to ad more fuel (sorry couldn't resist), to the story and some background..... I'm using a auxiliary fuel tank, with the VRO oil tank connected.
Just had to have my under-deck fuel tank pumped, so been using aux. tank most of season.

Maybe the aux. tank and VRO is causing excessive oil dump into gas mix?
Just a guess !

Thoughts?

I don't think it's a fuel restriction. Did the air leak theory provide any more detail?

[bigdog]

Sorry DaveR, the article didn't provide any more details, other than what I previously stated.

BTW, took the boat out today on Winnie, what a gorgeous day, no wind, flat water, but the humidity was oppressive !

When I started the engine, it smoked some at the dock, but not over smoked. Of course the engine was cold, and I guess that's normal behavior of 2 strokes, until they warm up.

Ran engine at about 4000-4500 RPM's, and it didn't miss a stroke, just runs great, and remarkably smooth.
Stopped at a couple islands along the way, for lunch and a swim, motoring at wake speed with little or no smoke.

Being my first year with an outboard, and a 2 stroke at that, what I do notice is it uses a lot more gas that my 4.2L Mercruiser.

Will continue to monitor smoke issue for rest of season. Still a few good w/e's before I have to winterize....

[Dave R]

Originally Posted by bigdog

Sorry DaveR, the article didn't provide any more details, other than what I previously stated.

BTW, took the boat out today on Winnie, what a gorgeous day, no wind, flat water, but the humidity was oppressive !

When I started the engine, it smoked some at the dock, but not over smoked. Of course the engine was cold, and I guess that's normal behavior of 2 strokes, until they warm up.

Ran engine at about 4000-4500 RPM's, and it didn't miss a stroke, just runs great, and remarkably smooth.
Stopped at a couple islands along the way, for lunch and a swim, motoring at wake speed with little or no smoke.

Being my first year with an outboard, and a 2 stroke at that, what I do notice is it uses a lot more gas that my 4.2L Mercruiser.

Will continue to monitor smoke issue for rest of season. Still a few good w/e's before I have to winterize....

I like Winterizing an outboard, nuthin' to it. I think your engine even has spray ports for fogging oil, right on the carburetors.

That motor will use about 15% more gas per HP produced than a 4 stroke, that's the downside of old carbureted outboards. The latest direct injection two strokes are remarkably efficient.