just bought pontoon boat with outboard.had jet boats ,i/o mercs and v-drive boats but this outboard thing is all new have a 1993 mariner 75hp. been sitting about 4 years got it home gave it once over hooked to hose put fresh gas and oil in it and she fired but ran kinda rough. if you rev it up was popping like a backfire through exhaust.not constant but quite often.so pulled carbs off took apart not as bad as i thought got em all cleaned out looking good inside and out put back together still does the same thing no change.pulled plugs looked ok but put new set in still no change.to me it seems like ignition is breaking down but not sure.is there a way you can check the coils? or any other ideas what to look for...
