loss of some power

[stock333]

Engine is a mercrusier 5.0 in a 23 SR. I was always able to get top end around 37 to 39 MPH.

Yesterday I went out and was only able to go no faster than 29 to 30 MPH.

Any suggestions on what you guys might thing have caused this.

Thanks

Mark

[shrew]

What are your Max RPM's reaching? Between 4400-4800? Has the Max RPM decreased as well?

Is the boat wet slipped or trailored?

[stock333]

Thanks for your questions to my question.

My RPM at full throttle are at about 4500RPM. It has not decreased. The boat is kept in a slip. The last time it was used was 2 weeks ago with no problem.

Thanks

Mark

[Phillbo]

Dirty hull....

[stock333]

Nope Hull Clean

Got to be something else

Thanks

[mmwjr]

My first thought would be marine growth as it doesn’t take much to kill performance. Next guess is bad fuel, did you recently refuel?

[Phillbo]

If the RPM's are unchanged it has to be increased drag or weight or maybe you've lost a cylinder?

When was the last time you looked at the plugs and wires?

[stock333]

Thanks for your reply. I was thinking the same think The last time I used the boat I filled it up with gas from a marina(very large one) that the gas was 40 cent less than I normally get. Drove back to my slip that was 15 minutes away with no problem. Then when I used it a about 10 days later for the first time with the new gas maybe that.s what happen. I was thinking the same thing. Any suggestion on what to maybe add to tank until I fill up the next time..

Thanks

Mark

[Phillbo]

https://www.amazon.com/STA-BIL-22240...000UJG0LE?th=1

[stock333]

Originally Posted by Phillbo

https://www.amazon.com/STA-BIL-22240...000UJG0LE?th=1

Thanks so much going to buy it and add to tank today

[mmwjr]

If you have a spin on fuel filter/water separator remove it and pour the contents into a glass jar to look for water.