4 stroke trouble

[Money Pit]

I bought a 05 90 HP Yamaha jet motor that I thought I got a great deal on. It had set for a year due to his bad health. I ran this motor for 2 to 3 hours starting and stopping and then it started losing power while running. I have now put in new fuel tank,Fuel,Filters,Injector Fuel pump, Had injectors cleaned and tested,Throtle cable and removed jet to check bearing. Still no top end power. I know this thing runs and I like it but it is costing me way to much money to figure this thing out.

[boats.net]

Have you checked compression, checked fuel pressure?

[Money Pit]

We checked pressure on it last wee k and did not read so we put it on his Mec. and read 47 psi. I ordered a new fuel pump motor and installed and did the same thing.

[boats.net]

If you can check fuel pressure at the time it is losing power and check spark with a timing light to see if losing fire on one cylinder. If the compression is not even then do a leak down test.