9.9 HP Mercury - Lots of Smoke

Barra · #1 March 27th, 2002, 04:16 PM

I have a 2 stroke 9.9 Mercury with two fuel tanks

I recently topped up my 2nd Fuel tank (1st time since buying the boat) with what I thought was premium unleaded - turned out to be Ultimate Octane Unlead (Octane Level 98). The manual mentions to use unleaded fuel with Octane levels above 87.

I used a 50:1 fuel to oil mix (12.5L to 250ml).

When running the motor off the 2nd fuel tank out on the water there was a fair bit of black smoke.. to the point the motor lost power and konked out.

I quickly turned back to the 1st fuel tank and the motor started.. no problems and no smoke.

After sailing around for the day I turned the motor back to the second tank.. now it ran fine with no smoke. So I figured it was the oil and fuel not quite mixed.

After 2 weeks of idle activity I start the motor again on the 2nd tank.. this time more black smoke.

I am wondering whether the Octane Level is way to high.

Any advice welcome

DJ · #2 March 27th, 2002, 04:23 PM

Barra,

I'm more concerned over "black" smoke as opposed to blue.

Barra · #3 March 27th, 2002, 04:40 PM

I couldnt ganantee the colour on that one. The smoke wasnt thick... maybe change to dark coloured smoke.