1978 Johnson 55 HP Outboards Service Manual, Page 17Get this manual
TROUBLE CHECK CHART TROUBLE POSSIBLE CAUSE AFUEL SYSTEMSee Section Fuel line improperly connected Engine not primed Speed control not advanced (throttle closed) Engine flooded Old fuel Clogged fuel filter screen Electric choke not operating Choke spring broken or disconnected Fuel system faulty BIGNITION SYSTEMSee Section Sensor coil Charge coils Power pack Sensor coil leads reversed Primary leads for ignition coils reversed Timing or linkage improperly adjusted Sheared flywheel key Ignition system faulty (key switch) CELECTRICAL SYSTEMSee Section Starter circuit faulty Wrong rotation (Bosch starter), brushes in wrong Gear shift not in neutral Defective neutral start switch Cranking speed too slow AREMOTE CONTROL Open lead (key switch to power pack) Faulty key switch Incorrect wiring harness Faulty power pack APOWER HEADSee Section Carburetors and ignition not synchronized Throttle control lever (won't advance) Air leak at manifold gasketswarped manifold (backfires) Broken leaf valves (backfires) Excessive carbon on pistons and cylinder head Stuck piston rings, or scored cylinder or piston BCARBURETORSee Section Old fuel, too much lubricant, dirt in carburetor Ignition timing screw loose Choke not operating properly Inlet needles and seats worn or stuck Incorrect carburetor float setting Incorrect orifice plug(s) Altitude horsepower loss CFUEL PUMP AND TANKSee Section Faulty fuel hose(clamps or seals)(kinked)(tank sitting on hose) Fuel tank or pump filter plugged Fuel filter restricted Fuel and vent valves not opening Valves not operating Fuel hose passages restricted Diaphragm leaking or damaged Anti-Siphon valves in built-in tank (incorrect or faulty) DEXHAUST GAS ENTERING CARBURETORSee Section Exhaust cover screws leaking Adapter gaskets leaking Cracked exhaust housing Exhaust adapter to cylinder screws loose or missing Plug in adaptor (starboard side) loose or missing