Re: engine slows down?
Reason I jumped right on the throttle tensioner as culprit is because that's initially where your description of the problem lead me.The fact that it gets slower and slower and you say you weren't touching anything.The symptom of gradually slowing down sounds a bit strange.Try eliminating a few possibilities.Insure the fuel tank is venting properly,insure there are no leaks in fuel line or fittings from tank to carburetor inlets,inspect the fuel tank pickup tube strainer for any debris,make sure the engine is running with fresh 87 octane or better gasoline and no water is present in fuel,Insure that before starting that the fuel primer bulb will pump up firm and hold,conduct a spark test at cranking speed on each plug lead and make sure it will jump a 1/2" gap to engine block or across tester points with a crisp blue snap.That should keep you busy on land for a while.Post back with your results.<br /><br />If you would have intermittently bumped the key switch primer button while experiencing this symptom while underway,it could have helped in diagnosing a possible carburetor/s restrictions.Also repeatedly squeezing the fuel hose primer bulb during this symptom could assist in ruling out a possible defective fuel pump.<br /><br />In short,lets make sure we're getting clean fuel and spark to each cylinder.Every known fact about this engines run history that you can think of would also be a great tool in helping us help you.<br /><br />I'm still not convinced that the throttle is not creeping back because of a tensioner issue.At the critical near planing speed of 3500 rpm,it wouldn't necessarily require a lot of throttle lever creepback to cause the boat to struggle which would lower the rpms even further.That leads me to wonder if this symptom would occur if you were holding the throttle lever at 3500 or advancing it further with no higher rpm results.
