Motor died after 1hr tolling

[Castaway]

Hi all,

Today I took the family for a cruise up the Ross River towards Kelso in my tinnie powered by a Yammie 30hp CV. Motor has just been serviced as it has not had a lot of use for a while and I have all new fuel. After about an hour of 6kts cruising the motor died. I had a little trouble starting it so I primed it again and off it went.

At home I looked at the sparkplugs and noticed they were quite black and had a good coating of oil. I also noticed the gap was more than the 1mm recommended gap.

Motor is about 10yrs old and in excellent condition. Any ideas on the cause of the motor dying? Would it be long period at trolling speed (4-6kts) or the sparkplug gap.

Mike

[finga]

Could be a number of things including what you said or could be the oil used in the fuel or the oil mixture ratio.
A good hard run is always good to blow the cobwebs out after a long trawl

[Chimo]

Hi Mike

I've had similar issues with a couple of my motors.
1 Half the power pack on one motor was sus which didn't give a real good spark so after a while it used to die. New plugs fixed it for a while but not for long as they blacked up. Solution was a new power pack.

2 If the plugs are fouling with slow running, which is an issue I have with another little motor I just adjust the fuel oil ratio. Finga hinted at this, I change the ratio from 50:1 to about 75 or 80: 1 and if your not flogging the motor it works fine and no more fouling. For hard running go back to 50:1 for safety.

Cheers
Chimo

[theangryangler]

had a similar issue with my 9.9 merc 2ST
try shakin up your fuel tank a bit especially if trollin in flat conditions
as your oil will settle in the bottom of your tank and the pickup
will suck it up and give your motor a straight shot of oil and STOP!!:P
once i started doin this no worries after........

[MattyDucati]

Recommended oil ratio for that motor is 100/1, it should have a sticker where the fuel line plugs into the motor. I also was running hotter plugs by one level.

[Castaway]

Thanks for all the advice. I will hopefully get out Tuesday and give it a good run and see if it happens again. The advice on this forum is always great and greatly appreciated.

Mike

[myusernam]

old fuel? doesn't take long. if so throw away.
clean carbies, new spark plugs, tin of engine tuner.
done

[testlab]

Was the tank vent open all the way? Sometimes they can get gummy and let a bit but not enough air in so give it a clean if you can (soak it in straight fuel and blow it out gently with compressed air).

[gr hilly]

if it had just been serviced and the plug gaps were wrong find a new mech.
Hilly