Honda BF25D Low power under load at open throttle

[Fishduck2]

Picked up a used, carbureted 2006 BF25D that looks clean. Motor runs fine with muffs but won't get up to speed when under load on the water on wide open throttle. Some things I have tried since getting it:

• Upper/lower oil and filter changed. Fuel filter and spark plugs changed.
• New fuel line and connection at motor (went to generic 3/8" line and got rid of the quick disconnect that was leaking)
• New fuel (97 octane, no ethanol)
• Disassembled fuel pump and found it to be clean and rubber in good condition. Cleaned with carb cleaner (after problems noticed)

Other notes:

• Electric choke was unplugged. I plugged it in. Same problems either way
• Fuel filter will sometimes drain under high rpm on muffs with a large air bubble forming. Returns to normal with small bubble after RPM drops
• I soaked carbs in concentrated seafoam (haven't tested since)
• I found a couple of hoses that are open ended in in the box. They seem to connect through T's to the top side of the carbs. They are the ones that go to "F8" in the attached image

My next thing would be a carb rebuild which I am hesitating at for now. Any advice is appreciated.

 

[racerone]

A compression test is step #1 on any motor.----Next is a spark check.-----Motor could be running on 2 of 3 cylinders.----And yes , it will rev up on 2 of 3 cylinders on a hose.----Perhaps motor was sold for a reason.