1981 Johnson/Evinrude 4HP Outboards Service Manual, Page 17Get this manual
TROUBLE CHECK CHART (CONT) TROUBLE LOS OF POWER (Cont) POSSI BLE CAUSE Pump housing seal damaged (5" adapter seals) Exhaust outl et gasket missi ng Exhaust housing gasket damaged ASPARK PLUGSSee Section Cover or inner terminal damaged (spark plug terminal out of HTlead) Foul ty leads Looselow torque Incorrect heat range Defective {cracked insulator} BMAGNETOSee Section Incorrectly adiusted points Loose iring Coil or condenser damaged (loose) Fibre breaker block wo rn Points dirty or pitted Defective breaker cam Loose armature pi ate screws or worn pil ot AMOTOR ADJUSTMENT Incorrec tilt angle BCAVITATION OR VENTILATION Protruding hull attachments Keel too long Transom too high CBOAT Imprope load distribution Marine growth on bottom Added weiqht (water absorption) Mismatched boat and motor (boat underpowered)
MOTOR MISFIRES (Providing Fuel SystemCarburetor K)
4POOR PERFORMANCE ON BOAT (Providing Motor Runs OK)