Many people do not realize this fact, but the rubber used to make tiller fuel lines will harden and become brittle over time. This happens because the tiller, and therefore the fuel line, is exposed to heat UV rays and gasoline. So in time, the fuel line will need to be replaced. This cannot be accomplished with any fuel line that you find in a hardware store. You will need to find out which fuel line size is required for the engine of your tiller. More often than not, the right fuel line will be available locally. One of the best places to look is at your local qualified service dealer.
Turn the fuel valve between the fuel tank and the carburetor off. Many tillers will not be equipped with a fuel on/off valve. If this is the case with your tiller, you will have to drain the fuel out of the tank. Use an approved fuel storage tank to store the fuel. Hang onto the fuel because you can reuse it after you replace the fuel line. Nothing will be wrong with the fuel. If you notice that water has made its way into the fuel, add an alcohol fuel additive so the water will burn off during normal operation.
Loosen the clip holding the fuel line in place on the fuel tank spout with a pair of pliers, and slide it away from the fuel tank over the fuel line.
Loosen the clip holding the fuel line in place on the fuel intake spout on the carburetor, and slide it away from the carburetor over the fuel line.
Pull the fuel line away from both spouts. Remove the clips from the old fuel line. Use the old fuel line to measure the correct length of new fuel line, and cut a new piece of fuel line with a pair of sharp scissors.
Slide the clips off the old fuel line and onto the new fuel line. Slightly heat one end of the fuel line with a heat gun (until it is more pliable) and slide the heated end of the fuel line onto the fuel tank spout. Slide the retainer clip into place to hold the fuel line onto the spout. Repeat the process with the other end of the fuel line.
Refill the fuel tank or open the fuel valve and check for leaks. Start the engine, and allow it to run for a few minutes to be sure the unit operates correctly with the new line installed.