Yamaha 150hp with very light blue smoke

[SouthAfrica75]

2001 Yamaha Outboard 150hp has excessive light blue smoke at each start up which diminishes after about 3 minutes. However you can still see very light amounts of light blue smoke after.

Any suggestions as to what this could be

 

[PatrickGold]

Re: Yamaha 150hp with very light blue smoke

If you have a 2-stroke, the only four things that can go in the cylinder are water, air, oil, and fuel. Fuel and water don't create blue smoke. The only thing it can be is the oil you are using. Most two-strokes smoke a little when they first crank. BTW... water can get into cylinders, but that is a really bad thing!!

If you have a 4-stroke, the only four things that can go in the cylinder are water, air, oil, and fuel. Again, fuel and water wouldn't create a blue smoke. I was told by a leading Yamaha technician that when a 4-stroke is trimmed all the way up and the engine bounces around a lot, a very slight amount of oil can get into the cylinder through the valves and cause a slight smoke when the engine is first cranked, but it shouldn't continue to smoke after the engine is initially cranked. Smoking for more than a minute is a sign of a problem with a 4stroke. Again, if water is in the cylinder, you have a big problem.

 

[rodbolt]

Re: Yamaha 150hp with very light blue smoke

you gotta explain this valve thing to me.
I still cant see oil defying gravity even if its trimmed up,. I realize most yamaha 4 strokes dont use valve stem seals, however oil runs off the valve fairly rapidly and heads for the sump. most the 4 stroke restart smoke us due to the engine left in the full down position and oil on the cyl wall behind the piston now heads downhill,past the rings and into the cyl. then its burned on the next restart.
excessive smoke at start up on the 2.6L yamaha can either be an oil pump shaft leaking,leaking oil line check valves or bad recirculation check valves.
however smoke at start up is common with carbed and most EFI two strokes, even the HPDI smokes a bit.
the optimax motors from merc not as much and my 175 E-TEC has never smoked at startup.
without seeing it its hard to say what is excessive.
what happens is at warm shutdown the fuel vapors tend to evaporate and leave the oil behind, at the next start cycle the puddled oil in the intake and crankcase get pulled into the cyl with the fresh fuel/oil mix and burns off. takes a minute or so to burn off this excessivly rich oil mix.

 

[SouthAfrica75]

Re: Yamaha 150hp with very light blue smoke

Thanks to the replies so far.

It is a 2 stroke with carb.

Never had this problem until the end of last summer.

Also failed to mention is that I'm burning a lot more oil and having to refill more than usual.

My wife, I and people at the dock or where ever we maybe want to run for gas masks when I crank up.

 

[Asainz320]

Re: Yamaha 150hp with very light blue smoke

Ok something very similar thing was happening to me. I also have a 150hp yamaha and when i started it for the first time it would make a lot of smoke for the first minute or two. The problem was the oil pump. It was letting the oil in the main tank leak to the inside of the engine, then when you start the engine this smoke is burned causing the excess smoke. Rodbolt told me it was probably a dirty valve inside the pump, so i changed the pump and the problem was fixed. Hope that helps.

 

[rodbolt]

Re: Yamaha 150hp with very light blue smoke

carefully check the pump adjustments, if its ok then replace the pump shaft seal.
they can leak and allow oil into the crankcase creating excessive smoke and consumption.

 

[SouthAfrica75]

Re: Yamaha 150hp with very light blue smoke

Rodbolt and others... thanks for the info.

Rodbolt, sure you dont want to head down to Ft. Lauderdale and help out

I'll have to locate a repair manual so I can get deeper into the oil sytem. I can do minor things on my own, but I think it's time for the manual to help out.

 

[kenco1]

Re: Yamaha 150hp with very light blue smoke

2001 Yamaha Outboard 150hp has excessive light blue smoke at each start up which diminishes after about 3 minutes. However you can still see very light amounts of light blue smoke after.

Any suggestions as to what this could be

are you using synthetic oil or an additive like slick 50 or prolong. dont do that and use regular oil 10w- 40. see kenco1's posting