You have a 99.99% chance of the carburetor orifices being clogged up. You will have to remove the carburetor and disassemble it before dipping the body and metal parts in carburetor cleaner. Under no circumstances can you place the plastic, rubber or fiber parts in cleaner as that will either dissolve them or cause them to swell. Any Nissan, Tohatsu or Mercury dealer has parts for this model engine.
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