1993 Yamaha 200 HP 2 Stroke won't start after smoking heavily yesterday

[Blacktalon82]

1993 Yamaha 200 Hp
2 Stroke
200TXRR
6G6 UL 763768
900-950+ hours


Yesterday spent several hours on the water with no issues whatsoever. Came back in for a short storm to pass, then headed later that night to the marina to put it on the trailer and the motor was smoking a lot even after warm up and while underway. This old yami isn't a smoker usually at all, and has been very reliable so it was very odd to see all the smoke. It didn't smell off, tell tale was still pissing strong, and it did not cause the motor to run roughly or hesitate to start. The smoke was lighter in color toward white-ish.

Today however, after a long drive to fish the Chesapeake bay the boat refused to start when we put in. Tried everything I could think of, and eventually flooded the motor from repeated tries Took off the cover and the air intake to let it air out...then tried again. Would not turn over, just sit and try and try and try. A couple times it coughed a little smoke, but nothing more than that. I've gone over the engine (as close as I could while on the ramp) and only found a small crack in the fuel filter housing slightly leaking gas. Nothing else looked out of place that was obviously off.

I'm at a loss as this motor has been nothing but reliable. The heavy smoke had me concerned, the non start has me even more worried, so I was hoping for some help. What would be the order of things to check from these symptoms?

Thanks in advance.

 

[99yam40]

motor will not start
compression, spark ,and timing of that spark.
if all of that is good then you are left with fuel
check fuel pressure,pumps, filters,and look for air being sucked into the fuel pump/system

 

[Blacktalon82]

I'll be digging out my old compression tester, and timing light today. I haven't used them since I had my old carb'd camaro in high school...but I assume the principles of timing/spark advance are the same as in a car. I have a Seloc manual to get the correct specs from, and understand the basics of engine repair so I am hoping an outboard isn't too different.

 

[Blacktalon82]

Had a guy at the ramp suggest water getting in through the lower unit could cause the issue. Any truth to that?

 

[99yam40]

I do not see how water in a lower unit would affect the motor starting or running

 

[tommarvin]

Hope it's not the head gasket.
It's easy to test for water in the lower unit,slowly remove the drain screw, any water will come out first in the first teaspoon drained.
If water is in the lower unit, drain and refill with new factory seals on drain and fill.

 

[Blacktalon82]

Compression test came back fine. Port side ranged from 110-112 psi and starboard from 115-117. Plugs were consistent, no major fouling or off coloration but were oil heavy in smell. Starter held 9.5 volts at crank and spun up in to flywheel fine.

 

[99yam40]

what do you mean by Starter held 9.5 volts at crank and spun up in to flywheel fine. ?
did it not engage the flywheel and turn the motor over?
9.5 volts is low

check battery and all battery connections

 

[Blacktalon82]

Ok, maybe should have explained that better.

Measured at the starter motor during cranking load at 9.5v, bendix gear engaged the flywheel and attempted to turn the motor over. Battery is at 12.7v, dipping to 11v during cranking, but it is my understanding that during cranking the correct voltage at the starter motor is 9.5. Battery is new as of March, I went through all the battery connections making sure they are all sound, and added a second battery for house loads yesterday which was already a scheduled upgrade for this season. Battery side is all new, and squared away.

I think I have found at least a few problems during pouring over the motor over the last few days.

1. The connection to the starter motor relay was very loose and not even finger tight. This no doubt loosened with the vibration of the long trailer ride and caused the no start condition. After the motor mechanically checked out as was operating properly I turned my attention elsewhere and found the loose nut. After correction the motor started properly.

2. The housing for the fuel filter is still leaking and causing a loss in pressure I would assume. It is on the supply side of the motor before the fuel pump. I ordered a replacement but what they shipped me did not match the part on the motor. Still needs replacement.

3. Motor still smokes during operation now that I can get it started. I know two strokes can, but mine never has once it warms up and now it constantly smokes a fair bit at all rpms and operating temps. I replaced the spark plugs since I had a set sitting around to rule out fouling and there was no change.

Operation:

The motor starts now as it did before, although I have to juice the throttle to about 1300 rpms until it warms up to keep it from coughing and dying at slow idle. If I couldn't see the smoke, I wouldn't know there was any issue during operation. Motor runs once it is warmed up but I don't want to ignore the symptom of the new smoking condition. It just has a bit of an issue at slow idle and will die with a big "cough" for lack of a better description. It fires right back up afterwards however.

A few good improvements, and thanks for the continued help with this!


Matt