QuestionI have a Sears, Model No 502.256114, riding lawnmower.
I believe it to be from the 80's. It does not run. Is there any troubleshooting tips you can provide me. I have never dealt with a riding lawnmower before and do not even know where to begin. It's a pull start. It looks like the spark plug is brand new, but I do not know how to tell if it is the correct one.
Any help you can provide would be appreciated.
AnswerPhebe,Phebe,Phebe
From friends.......Wow I am Honored..........:-}
The following chart lists a variety of common problems and nearly all possible causes. Diagnostic procedures will then be needed to determine which actually apply. The 'possible causes' are listed in *approximate* order of likelihood.
Problem: Engine will not start or is hard to start.
Possible causes:
Fuel tank is empty or shutoff valve is closed, or fuel line or fuel tank cap vent is clogged.
There is water in the fuel.
Carburetor is overchoked.
Carburetor is improperly adjusted or needs service.
Ignition system or its wiring is defective or ignition switch is off.
Deadman or other cutoff switch is open or defective.
Spark plug is fouled, improperly gapped, or damaged.
Engine compression is poor.
Operator needs to read user manual. :)
Problem: Engine starts easily but dies after a few seconds.
Possible causes:
Fuel tank is empty or shutoff valve is closed, or fuel line or fuel tank cap vent is clogged.
Carburetor is overchoked.
Carburetor is improperly adjusted or needs service.
Problem: Engine idles roughly, unevenly, or surges.
Possible causes:
Carburetor is dirty.
Air leak in carburetor or intake manifold (e.g., bad O-ring, gasket, primer).
Carburetor is improperly adjusted or needs service.
Problem: Engine misses under load.
Possible causes:
Spark plug is fouled, improperly gapped, or damaged.
Breaker points are pitted or improperly gapped, breaker arm is sluggish, or condenser is bad.
Carburetor needs adjustment or service.
Fuel line, fuel filter, or fuel tank cap vent is clogged, or fuel shutoff valve partially closed.
Valves not adjusted properly or valve springs weak.
Exhaust ports blocked (2 stroke).
Problem: Engine knocks.
Possible causes:
Magneto is not timed properly.
Carburetor is set too lean.
Engine has overheated.
Carbon buildup in combustion chamber.
Flywheel is loose.
Connecting rod is loose or worn.
Cylinder is excessively worn.
Problem: Engine vibrates excessively.
Possible causes:
Engine is not mounted securely.
Blade or other driven equipment is unbalanced.
Crankshaft is bent.
Counterbalance shaft is not timed correctly.
Problem: Engine lacks power (possibly after warmup).
Possible causes:
Old gas, bad spark plug, very thick/dirty oil.
Choke is partially closed.
Carburetor needs adjustment or service.
Ignition not timed correctly.
Air filter is clogged.
There is a lack of lubrication.
Valves are not sealing properly.
Piston rings are not sealing properly.
Head loose or head gasket blown or damaged.
Exhaust ports blocked (2 stroke).
Problem: Engine operates erratically, surges, and runs unevenly.
Possible causes:
Fuel line or fuel tank cap vent is clogged.
There is water in the fuel.
Fuel pump is defective.
Governor is not set properly, sticking, or binding.
Carburetor needs adjustment or service.
Loose carburetor/intake pipe resulting in vacuum leak.
Problem: Engine overheats.
Possible causes:
Magneto is not timed properly.
Carburetor set too lean.
Air intake or cooling fins are clogged.
Shroud or blower housing missing.
Excessive load.
Insufficient or excessive oil.
Improper oil viscosity (4 stroke) or mixture (2 stroke)
Valve clearance is too small.
Excessive carbon buildup in combustion chamber.
Problem: Crankcase breather passing oil.
Possible causes:
Too much oil in crankcase.
Engine speed is excessive.
Oil fill cap or gasket is damaged or missing.
Breather mechanism is dirty or defective.
Piston ring gaps are aligned.
Piston rings are worn.
Problem: Engine backfires.
Possible causes:
Carburetor set too lean.
Magneto is not timed correctly.
Valves are sticking.
