The recoil starter rope on old outboards was the only way to turn the engine over fast enough to create spark and combustion. A spring inside the recoil starter housing keeps the pulley under constant pressure, to keep the rope retracted and coiled. If the rope breaks and retreats within the housing, you have no way to start the engine. The old outboard engines with the recoil mechanism can be disassembled easily to repair the recoil mechanism and replace the rope.
Transport the boat to a convenient work location on a trailer. Unsnap the fasteners on the top engine cowl by hand. Push the lid back. You will see the starter mechanism housing is held in place with four bolts, which have screwdriver heads or bolt heads. If part of the rope has become tangled around the pulley mechanism, pull it free from the pulley or cut it away with scissors.
Unscrew the screw heads or bolts that hold the housing in place, with a screwdriver or socket and ratchet. Turn the housing upside down and examine the pulley and winding. Look for the knotted end of the rope, called the "bitter" end, on the circular plate where it attaches. Pull it out. Use a large screwdriver to loosen and remove the centre bolt to the top of the sheave. After it is removed, you will have two circular pieces of the housing that sandwich together.
Inspect the bottom housing. Ensure the recoil spring sits inside the recessed track. If it has popped out, gently wind it, starting from the outside. When it is wound, tuck the end of the spring that has the clamped end in the outside notch of the lower housing.
Cut about 6 feet of new 1/4-inch nylon rope with a pair of scissors. Burn both ends of the rope with a cigarette lighter. Thread one end of the rope though the outside guide in the engine cowl case, and leave it unattached next to the sheave pulley. Place the upper housing over the bottom housing; ensure the ratchet and socket between the two engages. Replace the centre screw or bolt, and tighten it with a screwdriver or socket.
Stabilise the lower housing with your knee, so it does not turn. Wind the top housing until it can go no further. Use a nail to push down through the upper housing sheave into the lower housing sheave to keep the spring tension from unwinding. Tighten a pair of vice grips on the end of the sheave, to immobilise it if you have no guide holes. Run the end of the rope (bitter end) into the sheave hole and tie it in a square knot. Align the rest of the rope slack so it will feed onto the pulley after you release tension on the spring.
Stick the rope through the pull handle grip; knot the end in a square knot. Carefully pull the guide nail out, or release tension on the vice grips while holding the upper housing by hand. Gently let the rope retreat onto the pulley, as you let the pulley sheave wind back down. Replace the screws or bolts on the top of the upper housing sheave, and tighten them with a screwdriver or socket.
Realign the engine cowl case with the top of the motor. Secure the fastening snaps. Test the pull rope by giving it a firm tug. The rope should retreat into the case. After you pull on it, the engine should turn over.
If the recoil spring has snapped, purchase a new one and rewind it back into the casing.