I have a 2007 skeeter zx20 bay boat with a Yamaha 150 4 stroke. Just bought this and it was stored for a year or so, I cannot get but 4300 to 4500 rpms out of the motor and it will not go above 23 to 25 miles per hour. Had a mechanic look at the motor and he said injectors were all working good as was the coil. Engine starts good, runs good, just doesnt seem to have the power needed. He suggested I had to big of a pitch prop on it, I have a M20 (20 " pitch 4 blade ss) . any advice would be appreciated

Need to drop down to a 15”-16” prop. Thats a lot of boat for a 150. Propped correctly it should hit low 40’s depending on load.

Thanks a bunch

the prop you have on it is the correct prop you have a power problem with the motor.

i'd start with low pressure fuel pumps and cleaning O2 sensor , i have a 2004 model behaving same way and this fixed me up. Simple to do in about an hour and cost $100

Are you trimming the engine up as you get going faster?

Ok, so my brother in law had a similar issue with his Yammie 4 stroke 150. Turns out those motors have to use a very specific type of fuel hose or else they will suck closed and restrict fuel. We had bought a hose from Walmart, one of those ones with the bulb built in and that was the problem. Took it to multiple mechanics to find the problem and when the last guy saw the fuel line, he instantly knew what was happening.

Do not sleep on this, make sure it’s the appropriate fuel line.

Disregard my advice. I was thinking the F150 had a 1.75 ratio not a 2.00.