You pull the starter cord, and your lawn mower engine spins with life, but it just won’t catch and run. It’s a common and deeply frustrating situation. You know the engine has the mechanical potential to start, but something in the fuel or ignition system is holding it back. Before you resign yourself to an expensive trip to the repair shop, there are several simple checks you can perform yourself. This Lawn Mower Turns Over But Will Not Start: A Troubleshooting Guide will walk you through the most likely culprits, starting with the easiest fixes first.
Think of your mower’s engine as needing three key things to run: fuel to burn, a spark to ignite it, and air to breathe. When it turns over but refuses to start, one of these three elements is missing. The good news is that the problem is often simple and inexpensive to resolve. By following a logical process, you can often diagnose and fix the issue in your own garage, saving both time and money.
Your Step-by-Step Lawn Mower Turns Over But Will Not Start: A Troubleshooting Guide
Let’s break down the diagnostic process into manageable steps. Always remember to disconnect the spark plug wire before performing any work to ensure your safety.
Check the Obvious First: Fuel and the Carburetor
Old or contaminated fuel is the single most common reason a mower won’t start. Gasoline can begin to degrade in as little as 30 days, forming gums and varnishes that clog the tiny passages in your carburetor.
First, check the fuel tank. Is there fresh gas in it? If the fuel is from last season or has been sitting for months, drain the tank and the carburetor bowl completely. Refill with fresh, clean gasoline. If the mower still won’t start, the carburetor’s main jet is likely clogged. You can often clear it by adding a fuel system cleaner to the gas tank, but a persistent clog may require removing and cleaning the carburetor.
Is Your Engine Getting a Spark?
If your fuel is fresh, the next step is to check for a spark. Remove the spark plug and reconnect it to the spark plug wire. Carefully lay the metal body of the plug against the engine’s metal block. Pull the starter cord and look for a bright blue spark jumping across the plug’s gap.
No spark? You’ve found the problem. The issue could be a fouled or damaged spark plug—an easy and cheap replacement. If a new plug doesn’t spark, the fault may lie with the ignition coil, which is a more advanced repair.
Don’t Forget the Air Filter
A clogged air filter can choke your engine, preventing it from starting by restricting the airflow it needs. Locate the air filter cover, usually a small box on the side of the engine. Remove the cover and take out the filter. If it’s a paper filter, hold it up to the light. If you can’t see light through it, it needs to be replaced. If it’s a foam filter, wash it in warm, soapy water, let it dry completely, and then apply a light coating of fresh engine oil before reinstalling.
Safety Switch Malfunctions
Modern lawn mowers have several safety switches that can prevent starting. A faulty brake safety switch or blade engagement switch might be interrupting the spark. While these can be tricky to diagnose, it’s worth checking your owner’s manual to understand how these systems work on your specific model.
Getting Your Mower Running Again
In most cases, the solution to a non-starting mower that turns over is found in the fuel system. By methodically checking for fresh fuel, a strong spark, and a clean air filter, you are addressing over 90% of the potential issues. Start with the simplest and most common causes, and you will likely have your mower back to cutting grass in no time.