When your lawnmower is stone cold, do you have trouble starting it? The reason for this is that, when the mower sits unused for a while, the fuel in the carburetor evaporates. By priming the carburetor, you will inject some fuel into its float bowl, which should allow you to start the engine. If you have never done this to your lawnmower before, these instructions should be able to help you out:
Step 1: Remove the cap from the fuel tank and make sure that there is plenty of fuel in there. If not, fill it up with petrol and replace the cap.
Step 2: Locate the primer bulb, which should be to one side of the lawnmower’s engine. It is usually red and can be found underneath the carburetor, which should make your search much easier.
Step 3: Once you have located the primer bulb, you will need to give it a press three times in order to prime the carburetor.
Step 4: Pull the throttle lever to the fast position, then grab the starter cord and pull it slowly until you begin to feel some resistance. Then, hold the throttle bar against the lawnmower handle with one hand and pull sharply on the rope with the other to start the engine.
It may take a few attempts to actually start a cold lawnmower. If, however, after three pulls the engine still has not started, you will need to re-prime the carburetor. The next time your lawnmower has been sitting stagnant for a few months and is simply refusing to start, give the carburetor a prime and see whether this fixes the problem.