1971 Evinrude Fisherman 6HP outboards Service Manual, Page 12Get this manual
TROUBLE CHECK CHART (CONT) TROUBLE POSSIBLE CAUSE APOWER HEADSee Section Carburetor and magneto not synchronized Throttle control lever (won't advance) Air leak at manifold gasketswarped manifold (backfires) Broken leaf valves (backfires) Cracked carbon seal (water in cylinders) Excessive carbon on pistons and cylinder head Stuck piston, rings, or scored cylinder Drain holes estrictedleaf stops bent closedshould open .040plug fouling BCARBURETORSee Section Poor fuel mixtoo much lubricant Carburetor adjustment(too leanbackfires) (too richexcessive fuel) Linkage screws loose Boss gasket leaking Air leaks at packing nuts Inlet needle and seat worn or sticky Incorrect carburetor float setting Incorrect orifice plug CFUEL PUMP AND TANKSee Section Faulty fuel hose (poor clamps or seals) (kinked) Fuel tank or pump filter plugged Fuel filter restricted Fuel and vent valves not opening Valves not operating Operating hose passage restricted Diaphragm leaking or damaged Fuel system hoses plugged "0" ring damaged DEXHAUST GAS ENTERING CARBURETORSee Section Exhaust cover screws leaking Cover plate gasket damaged Exhaust relief obstructed Adapter gaskets leaking Cracked exhaust housing Exhaust housing to adapter screws loose or missing EOVERHEATING POWER HEADSee Section Exhaust cover gasket leaking Inner exhaust cover leaking Head gasket leaking (warped head) (water in cylinders) FLOWER UNITSee Section Water intakes obstructed Pump housing air bleed restricted Water passages obstructed Pump plate not sealing (bottom) Pump impeller damaged Pump housing or plate worn Water tube grommet loose GEXHAUST GASES ENTERING COOLING SYSTEM See Section Pump impeller plate not sealing (bottom) Damaged water tube grommets or "0" rings Exhaust housing gasket damaged