1972 Johnson 2HP Outboard Motor Service Manual, Page 15Get this manual
3MOTOR MISFIRES (Assuming Fuel SystemCarburetor
SPARK PLUGSee Section Cover or inner terminal damaged (spark plug terminal out of H.T.lead) Faulty leacl Looselow torque Incorrect heat range Defective (cracked insulator) MAGNETOSee Section Incorrect1y adjusted points Loose wiring or condenser damaged (loose) Fiber breaker block worn Points dirty or pitted Defective breaker INCORRECT PROPELLER Incorrect tilt angle (smoking) Poor fueltoo much lubricant(smoking) Bent or worn propeller Exhaust outlet clogged Bent gear housing or exhaust housing (broken driveshafts) Altitude horsepower 10ss Exhaust leaks Overheating CAVITATION Protruding hull attachments Keel too long Bent prope11er (vibration) Transom too high Improper load distribution Marine growth bottom Added weight (water absorption) Hook in bottom