HELP SPARK PLUG BREAKING DOWN

[wazzy]

"Can any one please help with

"Can any one please help with info.

The bottom S/Plug on my one motor (25 hp pull start) keeps on breaking down. Have checked the fuel pump , carbs,jets and compression tested all cylinders. All is fine

THe plug last for about half a day of trawling/ running around( around one tank of gas) running 100:1 premix.

When I take it out it's wet and not overly carboned up

Any idea's

Rgds
Waz"

 

[grahamr]

Maybe bad fuel pump diaphragm

Maybe bad fuel pump diaphragm allowing raw fuel to get sucked into that lower cylinder and wetting/fouling plug. Pull fuel pump off and check it. Also if thermostat is not allowing motor to reach normal temperature can create rich fuel mixture and foul plugs. Good Luck