78 johnson 70 hp

[Cwsanders]

Have a problem with fouling the plugs. I took boat to lake last weekend and drove a good bit. Boat was running good. Then started across lake and lost 1 cylinder than another. Finally limped back to boat ramp on 1 cylinder. Got home changed plugs. Ran good for about 15 minites then did the same thing again. I know my gas is a little rich but not too rich. What could be the issue. What should i check?

 

[racerone]

Step # 1 is to test compression.----Then check for strong spark on all 3 leads.-----Strong spark on these is spark that will jump a gap of 3/8" or more.---What is the history on the motor ?-----How long have you owned it ?-----Did it sit for years with fuel in the carburetors ?

 

[Cwsanders]

I have owned it for 3 years. I use it about every weekend. It does not sit very much. I will try check the spark tonight. I kinda have a feeling it is not strong enough.