Fuel, fire and air are the main components for operation of any combustion engine. When troubleshooting a Briggs & Stratton engine, the same holds true. Fuel must reach the combustion chamber for the engine to fire. Fire is created by the spark of the spark plug which is generated by a magnet on the flywheel. Air is the last component that is needed for any fire. As with no air, no fire or combustion can take place. By following basic logic, you should be able to troubleshoot a Briggs & Stratton engine, or take on any small engine repair for that matter.
- Skill level:
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Things you need
- Old coffee can
- New fuel filter
- Fresh petrol
- Socket set to fit spark plug
- New spark plug
- Philips or slotted screwdriver
- New air filter
- Clean motor oil
- Clean rag
Pull the fuel line that goes to the engine's carburettor. This will be a 6 mm (1/4 inch) diameter rubber hose. There should be a small spring clamp that can be loosened by using the pliers and crimping the two exterior spring ends together and moving the hose clamp away from the carburettor connection.
Inspect that fuel flows freely from the hose. If it does not, check the hose for a blockage. If the Stratton engine fuel line has an inline fuel filter, it may need replacement.
Check the odour of the petrol. It should smell fresh and crisp to the nose. It is smells like "old varnish," the fuel has gone bad and needs to be flushed from the fuel tank.
Replace the old petrol with fresh petrol on the fuel tank and reattach the fuel hose to the carburettor.
Pull on the starter cord. If the engine fires, you have found the problem. It not, proceed to the next section on "Fire".
Using the proper size socket set, remove the sparkplug. The sparkplug resides on the engine between the cooling fins of the cylinder head. A long rubber coated wire ties the sparkplug with the engine's ignition system. Pull the plug wire loose. Remove the ceramic-topped sparkplug.
Inspect the metal portion of the sparkplug that was inside the engine. There will be a curved tip on the end that looks like the letter "J." Is the spark plug covered in a thick black soot and smells like petrol? If so, the engine has become flooded. The sparkplug is old and needs to be replaced.
Check the plug for a spark, if the metal end of the plug has a brown or tan colour and the "J" smells of petrol. Place the plug wire back onto the conducting tip of the spark plug.
Use the pliers and hold the plug against the metal part of the engine. The metal of the spark plug, the "J" end, should be in full contact with the metal of the engine.
Pull the starter cord while holding the plug in contact with the engine. Does a small white spark emit between the "J" end and the round tip of the plug? If it does, you have fire. If it does not, the spark gap or condenser of the ignition system may be bad. You will have to replace the condenser of the spark system.
Put the new spark plug into the Briggs and Stratton engine, and pull the starter cord. If the engine starts, you have found the problem. If not, proceed to the section on "Air".
Use the screwdriver, and remove the air filter cover that conceals the carburettor. The air filter will either be a foam type that can be cleaned or a paper type that should be replaced if dirty.
Clean the foam filter with a hot soapy water solution to remove any dirt and grime that can accumulate from heavy use. Allow the foam to dry completely before replacing it in the air filter container.
Thoroughly soak and squeeze clean motor oil into the foam filter. The oil-soaked foam aids in catching fine particles that can become airborne.
Use a clean rag and wipe clean any foreign debris that may have gathered on the intake portion of the carburettor. Be sure not to lodge any particles down in the air intake tube.
Replace the air filter and the housing onto the carburettor. Pull the start cord. The engine should start.