1999 260 Sundancer perforamance issues??

[Captain Gary]

After getting out of winter storage everything on my 1999 260 Sundancer (injected 7.4 MPI with Bravo drive) fired right up and seemed fine just like last year while motoring slowly in the harbor to my slip. When I got out on the big water (finally!) and tried to run it up and get on plane, it didn't have the power. She seems to run fine up to about 1600-1800 RPM (and around 8 knts) but higher than that she just seems to dog with no power and will quietly "pop" occasional and just not run "right". I can only get her up to about 2800 RPM at full throttle in gear, well below normal, but there's not enough speed/power to get up on plane. She seems to run smooth to 4500 RPM+ in neutral. The Prop spins easily by hand when not in gear and nothing fouling it. I changed the fuel filer and cleaned the air intake filter unit but it didn't help. Any idea on the problem with no power above 1800 RPM when under load?

 

[Captain Gary]

Nobody has any ideas?

 

[bzbaz63]

Valves or valve springs.
Popping noise is a valve problem

 

[scoflaw]

Start with a complete tune up and a fuel pressure check. Test your compression while you have the plugs out

 

[Espos4]

Nobody has any ideas?

Lots of ideas.......
But more info would be helpful.
How many hours on the motor?
How long have you owned it?
Give us some maintenance history and any recent repairs.

Big difference between “I just bought this boat with 900 hours without a survey” and “Original owner, 320 hours and just did a compete tune-up”