2003 F115 seems low on power

[Partsme 8558]

I have a 2003 F115 4stroke Yamaha(F115 TXRB). Several issues in making my boat go. Its a 2003 Hurricane Fundeck 22 ft boat . I want to acheive at least 30 mph. Fastest I have gotten is 17 and slow down to 8mph. The engine will not turn over 4600 rpm. It is a 25" motor ona 20" transom which is not right I know. So to start with I have put a jack plate on it and is raised almost 8 inches with 4 inch setback. Didnt help any starting out with 17 pitch prop still not over 4600 rpm, so I changed to a 15 pitch prop and slowed down even more and still not turn over 4600 rpm. Then changed to a 13 pitch prop and slowed even more and still will not turn over 4600 rpm. So I dont think the engine is producing enough power like it should. So I run compression test about 190 lbs of pressure in each cylinder, new plugs, new injectors new vst filter and cleaned the vst chamber , fresh gas, 41lbs of fuel pressure at idle ,38 lbs of fuel pressure in gear and reving up on rabbit ears , turn it off and holds about 40 psi of pressure for a 30 to 45 seconds to maybe a minute or so. New thermostat, new temp sender new oil sender. New water pump , oil and filter change, lower unit gear oil change. No code using yamaha diagnostic software everything looks good using the software. The software reports the engine to have 130ish hours. I am at a loss dont know where to go to from there? Anybody have any ideas? Im leaning towrds the ecm but hate to spend 1000 bucks to just try and see. Help!

[exeter27]

I'm not familiar with these motors, but one thing quickly came to mind. Have you verified that your throttle cable is adjusted/connected properly? If it isn't fully opening the throttle - well there you go! Hope it's that simple.

[rodbolt17]

I am very familiar with not only the F115 but basterdized rigs.

only way to solve this is isolate the engine issue or hull issue.

only way to do this is buy,beg borrow or steal test wheel YB-1624.
install it.
back it down and full throttle it should spin 5600-5800.

if it wont either the tach is off or the motor has an issue.

if it will turn between 5600-5800 its a hull/ prop issue.

yep it is that fast and simple.

[RayBersch]

Check out the Yamaha Performance Bulletins for the Hurricane Deck boats. There is one for a 2010 22' with the F115 - it states top speed was 33 mph at 5,700 rpm with a 13 1/4 x 17 with a part #6E5 54945-01-EL. Check out the specs to see if that boat is close to yours. If you can't get a test prop then perhaps try the one listed in the bulletin. Consider that these tests are run with new boats so you need to consider your hull condition before you wish for 30 mph and you need to also consider hull improvements, if any, over the seven years from 2003 to 2010. Check the weight of the boat in the bulletin and see if yours is close - boats tend to gain weight with age - my pontoon boat has gained almost 300 lbs of stuff squirreled away somewhere or another.

[zenoahphobic]

Three different pitch props does not alter RPM! Surely something is wrong with the engine - some sort of limiter malfunction (not supposed be at 4600).

If you lifted the engine, as you said because 20 transom with 25 leg, and you have also moved it back, you could have cancelled any correction you wished to have achieved.

I presume at 17 mph the boat is just planning, meaning the water has cleared some distance past the transom. Check if you can even see the cavitation plate at full throttle. If engine still buried, it will need to be raised even further. Sticking an engine further aft can have a drastic affect on hull attitude. I'd also check weight (not full of water is it?)

[rodbolt17]

you can chase ghosties a long time.
you can isolate it very quickly with that test wheel.
while running it on the test wheel take a snapshot with YDS and see what the ECU is "seeing" and "doing".