There’s nothing more frustrating than a beautiful Saturday morning, a lawn in desperate need of a trim, and a mower that simply refuses to start. You pull the cord again and again, but all you get is silence or a sputtering cough. Before you resign yourself to a day of manual shears or an expensive service call, take a deep breath. With a systematic approach, you can often diagnose and fix the problem yourself. This guide is designed to walk you through that process, turning a moment of frustration into a satisfying repair.
When your trusty machine lets you down, it’s easy to feel overwhelmed. However, the vast majority of starting issues with gas-powered equipment like your DeWalt mower stem from just a few common culprits: old fuel, a dirty air filter, a plugged spark plug, or a simple safety switch being overlooked. By following a logical sequence, you can eliminate the guesswork. This DeWalt Gas Lawn Mower Not Starting: A Step-by-Step Guide will help you troubleshoot the issue safely and effectively, saving you both time and money.
Before You Begin: Safety First
Before we dive into the steps, your safety is the top priority. Always disconnect the spark plug wire before performing any inspection or maintenance. This prevents the engine from accidentally starting while your hands are near the blade. Make sure the mower is on a flat, stable surface and that the engine is completely cool to the touch. Having a basic toolkit with a socket set, screwdrivers, and a pair of gloves will make the job much smoother.
DeWalt Gas Lawn Mower Not Starting: A Step-by-Step Guide
Let’s walk through the most common causes in a logical order, starting with the simplest and most frequent fixes before moving to more involved checks.
Step 1: Check the Simple Stuff First
It may sound obvious, but it’s worth double-checking the basics. Is there fuel in the tank? Is the fuel valve (if your model has one) in the ‘On’ position? Most importantly, are you engaging all the necessary safety features? For the engine to start, the brake lever on the handle must usually be engaged. On some self-propelled models, the drive control also needs to be disengaged. Consult your owner’s manual for the specific safety requirements for your DeWalt model.
Step 2: Investigate the Fuel System
Bad gasoline is the single most common reason a small engine won’t start. Gasoline begins to degrade in as little as 30 days, forming gummy deposits that can clog the carburetor.
- Old Fuel: If the fuel has been sitting in the tank for more than a month, drain it completely. Use a siphon pump to remove the old fuel into an approved container.
- Fresh Fuel: Fill the tank with fresh, high-octane gasoline. Avoid using fuel with more than 10% ethanol (E10) if possible, as ethanol attracts moisture and can harm engine components.
- Clogged Carburetor: If you’ve confirmed you have fresh fuel and the engine still won’t start, the carburetor’s tiny jets and passages are likely clogged with old fuel residue. You may need to clean the carburetor bowl and jets or use a carburetor cleaner additive in the fresh gas. For persistent issues, a carburetor rebuild or replacement might be necessary.
Step 3: Examine the Air Filter
Your mower’s engine needs a precise mix of air and fuel to run. A dirty, clogged air filter chokes the engine, preventing it from starting. Locate the air filter cover, usually on the side of the engine, and remove it. Take out the filter.
- Foam Filters: If it’s a foam filter, wash it in warm, soapy water, rinse, and let it air dry completely. Then, lightly coat it with fresh engine oil and squeeze out the excess.
- Paper Filters: If it’s a paper filter, hold it up to a light. If you can’t see light passing through, it needs to be replaced. Do not clean a paper filter with water or compressed air, as this can damage it.
Step 4: Inspect the Spark Plug
The spark plug provides the ignition for the fuel-air mixture. Over time, it can become fouled with carbon, corroded, or the gap can become incorrect. Using a spark plug socket, carefully remove the plug from the engine. Inspect the electrode at the end.
- If it’s black and sooty, covered in oil, or has a cracked porcelain insulator, it needs to be replaced.
- If it looks reasonably clean, you can clean it with a wire brush and check the gap with a feeler gauge, setting it to the specification in your owner’s manual (typically around 0.030 inches).
- When in doubt, replacing an old spark plug is an inexpensive and effective troubleshooting step.
Step 5: When the Basics Don’t Work
If you’ve diligently followed all the steps above and your DeWalt mower is still not starting, the issue may be more complex. Here are a few other areas to consider:
- Oil Level: Many mowers have a low-oil safety sensor that will prevent the engine from starting if the oil is too low. Check the dipstick and top it off with the recommended oil type if needed.
- Flywheel Brake: The safety system that stops the engine when you release the handle can malfunction. Ensure the cable is connected and the mechanism is moving freely.
- Compression: While less common, an engine with low compression due to internal wear will not start. This is a more serious repair that may require professional service.
Keeping Your Mower Running Smoothly
The best way to avoid a non-starting mower is through regular, simple maintenance. At the end of every mowing season, or if you plan to store the mower for more than 30 days, either run the engine until the carburetor is completely out of gas or add a fuel stabilizer to a full tank. This prevents the fuel from breaking down and clogging the system. Regularly checking and replacing the air filter and spark plug according to the maintenance schedule will also ensure your mower is ready to go when you are.
By working through this logical sequence, you’ve likely identified the reason your DeWalt gas lawn mower wasn’t starting. Whether it was a simple tank of fresh gas, a quick air filter cleaning, or a new spark plug, you’ve not only saved a repair bill but also gained a better understanding of how your equipment works. With this knowledge and a little preventative care, you can keep your lawn looking great all season long.