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My outboard will not pull fuel into the carburetor. I have changed all fuel lines, diaphragms and rebuilt the carburetor. The only thing I did do was put a larger filter on the engine but was assured if the filter would fit within the casing, it was fine. The engine runs as long as I or my wife is periodically pumping the diaphragm to a tense position. It's a workable solution but not optimal. The engine is a 1997.

Any advice?
Thanks,
Bryan
 

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i also have a yamaha 9.9 but i've never really had an issue with the fuel,did this problem arise after u changed the filter or before?
,what happens when you ease out the choke while its already warmed up,does this help?if it is starving for fuel the choke should help temporarily,you might try running it without a filter for a short time,when you pump the bulb does it fill full or soft?i doubt what ever it is is serious,just keep thinking and trying different things
 

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Fuel pump getting weak?
 

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Give what you have tried, I would check these things, in this order

Check the antisiphon valve on the tank. Probably NOT the problem, since pumping the primer works. But if it is a little resticted, it can cause that symptom. You can simply bypass it for a test, but do replace it.

Let the fuel pump pump into a jar (take the hose loose from the carb). It should pump quite a bit; the manual has a spec, but will be something like 1 cup per minute.

Cover the end of the hose with a finger. Is there some pressure? I recall there is more than one pump for that motor and that the pump can be assymbled backwards (I don't have it in front of me). It's easy to get to so check that work. The pressure should push your finger off the hose (not too tight). Certainly more pressue than the primer bulb generates.

Air leaks. If a gasket or hose is imperfect on the suction side that will ruin it.

I run big Raycors on my 9.9s, so the filter size is not the problem.
 
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