The pull cord on a leaf blower helps get the engine started by cranking the flywheel. When the flywheel gets spinning fast enough, it will force the ignition module to discharge a high voltage spark to ignite the fuel. This pull cord can get stuck due to dirt, oil and other substances that may stick to the nylon fabric. The pulley and recoil spring may also break down, causing the pull cord to stop moving. The flywheel and crankshaft can also break down, causing the pull cord to stop moving.
Undo the mounting bolts on the back of the engine, holding the starter cover to the flywheel and crankshaft. Remove the screw and lift the starter cover off the engine; turn the cover upside down to access the pull cord.
Try turning the crankshaft and flywheel with your hand. If they don't move, seek a professional mechanic. If they spin, the problem is in the cord, pulley or recoil spring and can be fixed.
Press your thumb onto the pulley. Cut the pull cord just below the base of the handle and let the recoil spring unwind slowly if it's still under tension. Cut the knot on the base of the pulley and take the old cord off. Unscrew the pulley's retaining screw and slide the screw, washer and pulley off the starter cover.
Separate the recoil spring from the center of the pulley. Inspect the pulley for cracks, dents or warping. Check the recoil spring's ends for any damage. Replace the pulley and recoil spring if they're damaged or excessively sticky or dirty.
Push the end of the new pull cord into the center of the pulley. Push the end of the cord through the starter cover and the handle. Tie a knot at each end of the rope to attach it to the handle and the pulley. Wind the cord clockwise onto the pulley.
Leave about 10 inches of cord free. Twist a small loop into the extra 10 inches. Insert the loop into the notch on the pulley. Move the pulley and loop back and forth to hook the pulley onto the recoil spring.
Rotate the pulley three to five turns clockwise, or until you feel tension on the pulley. Hold the pulley down with your thumb and unhook the loop. Let go of the pulley and let the cord wind up on the pulley. Turn the cover over and attach it to the back of the engine.