How to Troubleshoot a Craftsman 5 HP High Wheel Trimmer

Wiggle the rubber boot off the tip of the spark plug, in the front of the trimmer. Unscrew the spark plug with the socket wrench. Take the spark plug out and insert the new spark plug, metal tip facing out, into the rubber boot.

Connect the ignition tester’s lead wire to the tip of the spark plug and to the spark plug hole. Set the ignition switch into the “On” position and pull firmly on the starter rope.

Look in the tester’s window for a blue spark. If there’s no spark, or the spark is yellow, service the ignition system.

Unhook the ignition tester from the spark plug and the hole. Screw the compression gauge into the spark plug hole until it’s finger tight. Pull firmly on the starter rope until the compression needle reaches its peak.

Watch the compression needle to make sure it goes above 100 psi and doesn’t fall back rapidly, indicating compression loss. If the compression decreases rapidly, service the internal engine components.

Unhook the air filter box on the back of the engine, near the fuel tank side. Pull the air filter and box off the engine. Reach underneath the engine to the carburetor and remove the two fuel hoses from the elbow connectors on the carburetor.

Tilt the engine backward and look for a small amount of gas to leak from the carburetor and hoses. If no fuel leaks from these areas, service the fuel system on the trimmer.