Yamaha 2 stroke 150 TXRB excessive exhaust smoke

[Messing About]

My 2002 Yamaha 150 TXRB 2 stroke suddenly started putting excessive exhaust smoke. I've owned it for 18 months and put well over 100 hours on it with no problems (has 400ish hours). I did lower unit service about 50 hours ago. 2 days ago I ran it about 20 miles at varying speeds and RPMs while fishing. At the end of the trip I ran wide open throttle for the last mile before the no wake zone. When I throttled down to 5 mph I noticed this awful smoke from the exhaust. The oil indicator gauge was flashing two lines but never alarmed. It continued for 2 miles of no wake speed then subsided for the most part but still showed more than usual blue/grey smoke the last half mile home. After flushing it and putting the boat on the lift I examined the unit. I found lots of residual oil on the outside of the lower unit. The main reservoir was nearly empty but the bottle on the outboard was full to the top line. I put a gallon of 2 stroke oil in the main res. The next day it started fine but smoked like crazy again. I let it warm up at idle for 10 min, no change. Revved RPMs, no change. Any thoughts?

 

[Capt Ken]

Re: Yamaha 2 stroke 150 TXRB excessive exhaust smoke

Be sure the main tank on the engine isn't overfull and overflowing into the engine intake. The aux in the boat is suppose to quit pumping at about 1/3 to prevent you from running dry. You do not get an alarm from the aux tank. Only a flashing warning. The alarm comes from the main tank getting low

 

[Messing About]

Re: Yamaha 2 stroke 150 TXRB excessive exhaust smoke

Here is a 10 second video showing what it looks like when running.
Notice that the exhaust smoke is coming from both the exhaust ports and the lower unit seal?

To answer your above question, yes when I start the engine the bottle fills up past the top line and seems to overflow. Although I don't know where the excess goes you probably do.

http://m.youtube.com/watch?v=huv8C6XgICQ

 

[99yam40]

Re: Yamaha 2 stroke 150 TXRB excessive exhaust smoke

Check to see if the link to oil pump from throttle linkage is still attached.
If it comes loose it will go full open at all times over oiling at low RPM.

 

[Messing About]

Re: Yamaha 2 stroke 150 TXRB excessive exhaust smoke

The rod is still attached that's not the problem. I have determined that the sending pump will not shut off no matter what.
Even when I hold the plunger manually to the top to fool it and make it think it's full, it's still filling with oil until I pull the plug wires to the pump.

What's the name of that plunger unit? Part number for a TXRB?

 

[99yam40]

Re: Yamaha 2 stroke 150 TXRB excessive exhaust smoke

1st thing to do is start testing to see if the level switches are working properly and that wiring is all intact.

Rodbolt and many others have posted in the past how to test , just need to do some searching and reading.

Service manual for your motor helps a lot

 

[Capt Ken]

Re: Yamaha 2 stroke 150 TXRB excessive exhaust smoke

If the engine tank is over filling then the float switch in the tank is bad. There is an over flow line off the top of the tank that connects to the breather.

 

[Messing About]

Re: Yamaha 2 stroke 150 TXRB excessive exhaust smoke

New float switch ($125) solved this problem. Thanks to all who helped diagnose.