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A smokinb Evinrude 15

T

trident

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"I have a 1990 Evinrude 15HP.

"I have a 1990 Evinrude 15HP. It starts OK, idles OK and in general it runs ok except it makes so much exhaust smoke that I'm sure I can be seen from the space shuttle! The gas/oil mixture is perfect but it produces an incredible amount of blue smoke and as well the fuel consumption is unbeleivably high. There is a lot of evidence of unburnt fuel in the form of "rainbow" spotting in the water. I am suspecting a lot of the fresh fuel/air charge is escaping from the crankcase through defective or worn seals in the crankcase head. This I think would definitely account for the high fuel consumption.Anybody have any ideas or comments on my diagnosis or similar experience?
In it's present condition the motor is unusable."
 
Sounds like it is obviously ru

Sounds like it is obviously running rich. Try setting the carb like the factory manual says. Other than that I would check the compression on both cylinders.
 
The carb settings are fine and

The carb settings are fine and even the plugs show
no signs of fouling. What should the compression
be in PSI?
 
"You got me. If it is burning

"You got me. If it is burning enough oil that you are putting mosquito patrol out of business, I would expect to see some serious deposits on the plugs. As far as compression, I don't know the numbers, but would expect from 85 to 100. What is more telling is if you have like 85 on one, and 65 on the other."
 
"Not to be obnoxious, but the

"Not to be obnoxious, but the last time my boat did this I realized that I had doubled-up on the oil. I put in oil for 100 gallons of fuel, then realized later on that I only bought 50 gallons. Is your mix known to be correct at 50:1 ?"
 
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