My boat sat up since the end of July of last year(18) untill March of this year when I took it out to run it. It ran ok but Inoticed that I couldn't get more than 5700 - 5800 rpm at WOT when in the past it was no problem to reach 5950 - 6000 rpm. I could load the boat down with people and gear and could get to 5950 - 6000 rpm no problem. I drained the fuel tank and put fresh fuel and ran it yesterday for most of the day. Again, it ran great but couldnt get more than 5800 rpm. My prop has a few dings in it but nothing out of the ordinary. Any thoughts? Could this be a fuel issue?
Prop RX4 15 x 20
Key West 230BR
05-28-2019 01:36 - edited 05-28-2019 01:40
This is just information, don't know if it applies to your climate in Key West.
If, when you got to the higher RPMs the general weather was cooler, less humid or higher air pressure , or any combination of those you gain power by the shear fact that more air is available to the engine. Up north where there are big temperature/ humidity changes between summer and spring/ fall I have seen 300 RPM differences.
Temperature and humidity and elevation (not in your case) play a large part in engine output. That is why they are rated for power using specific guidelines set by the organization ICOMIA. A warm muggy day can lower power several hundred rpm. Many of the Pro Fisherman use a different prop during the summer season than during the cooler spring and fall times of the year.
"There is never just one thing wrong with a boat";
-- Travis McGee, main character in a book series by John D. McDonald
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.
The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.