Riding Lawnmower Won’t Start? – Think Solenoid

If your lawnmower won’t start, you hear a clicking sound and you’ve checked all the usual suspects by insuring that the battery is fully charged and will provide the starting load, the spark plug is connected and none of the safety devices like having the machine in gear or the blades engaged are causing the problem, the next place to check is the solenoid. The solenoid is usually easily accessible and is an electromagnetic switch that engages when you energize the ignition – by turning the key to the start position.

If you lift the engine cowling and look to the rear of the engine you will see the solenoid. The positive (red) and negative (black) battery wires will be attached to it at heavy posts as well as some other electrical wires connected to smaller posts. First try gently tapping it with a rubber mallet. Sometimes this electromagnetically activated switch gets stuck. If that doesn’t work, you can try jumping the solenoid switch. The safest way is to take your battery jumper cables and using just one of the jumper wires, connect one side to the negative post (black) on the solenoid and then touch the other side to the positive post (red) of the solenoid. Make sure your key is in the on position and the lawn mower is otherwise ready to start. Be careful that the jumper wires do not become tangled as the engine starts. Also, someone sitting in the seat to prevent any mishap is the recommended and safest procedure.

CAUTION – this will immediately engage the starter and the lawnmower may start and begin running if the problem is the solenoid. Use extreme caution as this process may cause sparks. NOTE: It may disengage any safety devices on your mower so insure that the mower is not in gear and the blades are not engaged. How the safety devices are configured on each make, model and size of lawnmowers is a bit different. The object is just to isolate the solenoid and determine the problem. If the starter engages and the engine starts to turn over, you have discovered the problem and may not have to continue to crank the engine and start it. It only takes a momentary touch to determine if the solenoid is faulty.

I became aware of this possibility when having a problem with my lawn mower at the same time a local mechanic was fixing my car in our driveway. When he noted my problem, he came over and stated that the clicking sound associated with my lawnmower not starting was probably caused by a faulty solenoid if the battery was indeed fully charged. I watched him connect the single jumper cable, bypass the solenoid and like magic the mower started. He further advised that a solenoid was an inexpensive repair part and could easily be replaced. A trip to Home Depot where the solenoid was readily available for a few dollars followed by about an hour of work to install it resulted in success. I had changed the solenoid and the mower has performed well ever since. I saved a considerable sum of money and time as well as acquiring some knowledge that is worth passing on.

If you are not mechanically inclined or have any misgivings about this process – don’t do it! The object of this article is to provide information and my experiences. One can confirm and supplement this information by making Internet searches about lawnmower starting difficulties and see similar experiences concerning solenoid problems as well as other information that may be helpful.