I have an 87 Johnson 20hp that i've owned for a little over a year.Decided after re-building carbs<br />i'd do a decarb.I could only find the SeaFoam in a can so i mixed it up with a gallon of gas,placed my outboard in a trash bucket and fired it up.It released a lot of white-smoke but not much black smoke as i thought it might considering i've never done it and who knows if the previous owner did.Next time i'm gonna try the Seafoam in a spray can as it just takes to long for my 20 to burn a gallon of gas.(It took an 1.5 hours).Just wanted to say thanks to all you guys for recommending thiss procedure.My old compression tests were 115psi,118psi.Will post the new results after i'm finished.Thanks again
