1991 Yamaha Outboard Factory Service Manual 9.9 and 15 HP, Page 131Get this manual
TROUBLESHOOTING ENGINE DOES NOT START
There is no fuel in the carburetor Fuel tank Empty or fuel level is low Priming pump Cracked, Defective Fuel hoses Leakage, Flattened, Broken
There is fuel in the carburetor Fuel tank Fuel is deteriorated or dirty
Spark is weak Spark plug 1ncorrect gap, Carbon deposits, Dirty, Oily, Burned Plug cap Faulty, No contact Ignition coilDefective unit Defective Pulser coil Defective Charge coil Defective