2007 Yamaha F225 doesn't seem to be providing full power

[davepjr71]

When I bought the boat (Key West 2300WA) 2 years ago it ran well but the speed seemed very low based on talking to yamaha, Key West and some prop people. I thought it was an undersized prop issue so I purchased a prop that is supposed to go with my boat. Whne I first put it on I got better handling but the same speed (34 MPH). That was early last year.

Since then, the speed keeps falling. Top speed dropped to 28mph and now is 26 mph. The boat just plows through instead of riding high and adjusting the trim does nothing but drop speed since I'm already plowing so bad. All of this is with a clean bottom. Lately, the motor sounds like it's struggling to push my boat. So, I've started research and found some threads on clogged VST filters. Could this be my issue? I like owrking on my own stuff and have done things like replacing the impeller myself so any help on what to look for would be greatly appreciated.

[99yam40]

you can monitor rail pressure to see if there is a problem with restrictions up to that point,
but may be best to have someone hook up with laptop and see what they can find before throwing any parts at it and hoping

[Gadget72043]

225 Yamaha 4 stroke

I have a 2004 225 4 stroke on 225 Edgewater express and it is probably close to same weight and dim. as your boat.Top end full of( fuel 115 gal.)and gear is over 42 mph @5600-5800 rpm.I have had a problem with mine running rich since new and the plugs carbon up after only a few hrs.10-15When they carbon up the top end drops off 3 mph and the rpm. drops 100 -300 >The dealers have all had a shot at it and with no results!!!! they bill me for labor, for plugs and fuel filters and each time a bill $400-$500!!!!!What rpm is your motor turning at wot?Should be 5000-6000.My advise is to pull the plugs they can tell a lot!!!I am looking to solve my problem by replacing the ecm which I believe to be bad from day 1.We shall see .I have seen these motors run hard for 1000 hrs with no problems they certainly can do the job.The trick is to spend the time and find the problem and fix it, not to put a band aid on it and hope it will heal itself.Find a (real mechanic)if you can who will spend the time to do it right.I don't want it done fast. I want it done right!Remember if speed were everything rabbits would rule the world!Good luck.By the way Yamaha lube my butt I have heard it all and tried it all !Marine fuel only- no ethanol and still have carbon on plugs!

[rodbolt17]

buy an ECM, then find a real technician.
if its running rich its NOT an ecm issue.
you can spend 1000 bucks but its not going to help.
either YOU learn how and why the suck squeeze bang and blow thing works or you have to find someone who does.

its a stupidly simple open loop speed density EFI.
been about since at least the mid 70's.