Johnson 28 spl max RPM 2800

[teleman360]

Using my boat for the first time this summer over the past weekend. The first few runs on the first day were great then the next day it would not go over 2,800 RPM's at full throttle. It idles fine. I just cleaned and rebuilt the carburetor this spring. At full throttle the butterfly valve if horizontal and you can see fuel coming out the high speed tube. The primer bulb is firm and squeezing it underway makes no difference. I also manually primed underway with no change. The sound of the engine is a little off, but wasn't sure if that was the just from the hood being off. Any suggestions on where to look next?
Thanks

 

[flyingscott]

Check for spark and compression. Sounds like it is running on one cylinder.

 

[oldboat1]

Wearing a pair of work gloves, pull off the plug boots one at a time. If the motor shows no change, that lead is probably not firing. On the other hand, if you pull off a boot and the motor stops running, that lead may be the only one firing.

 

[teleman360]

So, if one cylinder is not firing what do I look at next? Spark plug, spark plug lead than ignition coil....

 

[oldboat1]

Pull the flywheel with a harmonic balancer puller. Replace coils if cracked. Replace points if pitted. I usually just replace coils, points and condensers with new, and go from there. If wires are old/cracked replace them with 7mm solid core wires. Check plug boots for cracks and replace if needed. (Not suggesting doing more than is needed, but easier to do it all than having to return a couple of times.)

If a single cylinder is a problem, I would check the point set first -- clean with some acetone on a match book cover or similar, and reset to .020.