2006 90 hp Yamaha 4 stroke

After running for a few minutes, motor intermittently bogs down & loses power. Starts fine, idles and slow speed fine. Already changed fuel and plugs. Any expert advice for a novice? I have to wait 3 weeks before the local boat shop can diagnose it and I’m not sure they’ll be able to do so in the regular boat “tub” they test in. If they have to take it to the river, I’ll be looking at a $300 fee for diagnosis. Trying to do everything I can before going that route.

Fuel delivery always comes to mind when one runs fine low speed or without a load. Loose fittings, cracked lines, clogged filter and screens are all suspect. That is the simple things to check before it gets more complex.

I read/learned here on TB about the liner coming apart in the fuel line from the gaso tank to the outboard. Hence restricting the flow of fuel.

LDUBS said:

I read/learned here on TB about the liner coming apart in the fuel line from the gaso tank to the outboard. Hence restricting the flow of fuel.

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Yes.. happened to me once with a 70hp.. motor would idle all day, but would only get half way up on plane.. changed the hose.. all good

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Is there a particular brand/type of fuel line this happens to? I have some Sierra fuel line that is light gray, and has a clear plastic liner. I have some typical SAE black fuel line, same size, much thicker wall, that does not have that liner.

The gray is junk.

Try pumping the primer bulb when it starts to act up, if it recovers from that, it is likely fuel pump related. Otherwise I am thinking injector, if it is not a fuel line issue.

I agree, that gray stuff is crap for bigger motors, but have never had a problem with it was small kicker-sized motors.

I don't know what class a 25 falls in but I got one once that stuff was on as a fuel line to the tank. It would suck completely flat.

I'm no expert by any means but I'd check connections to make sure it's not sucking in air and leaning out.

generally speaking if it's a fuel supply issue, it'll repeat the bog/die process exactly the same every time. Not always but usually.

Carburetor or EFI?

If it is, has it been sitting for any length of time?

How's the water pressure? When's the last time it had a water pump repair?