Quick Answer
To start a gas-powered lawnmower: Check fuel and oil levels, ensure the spark plug is clean, move the choke to the cold-start position, and pull the starter cord with one firm, quick motion. For electric mowers, fully charge the battery and press the power button. For manual push mowers, simply begin pushing with steady, even pressure. Always perform safety checks before starting any mower.
Safety Checks Before Starting Any Lawnmower
Before you attempt to start any lawnmower, take time to inspect the machine and your surroundings. These prerequisites apply regardless of mower type.
- Wear appropriate safety gear: Long pants, closed-toe shoes, and eye protection. Consider hearing protection for gas mowers, which typically produce 85–90 decibels.
- Inspect the blade area: Remove any debris, sticks, or stones from the cutting deck. A foreign object can damage the blade or become a projectile.
- Check the blade guard and discharge chute: Ensure they are secure and not cracked. Never operate a mower with a damaged guard.
- Clear the mowing area: Remove toys, rocks, branches, and other obstacles. Keep bystanders—especially children and pets—at least 25 feet away.
- Inspect the mower for damage: Look for loose bolts, cracked handles, or fuel leaks. Do not start a damaged machine.
- Check fuel freshness (gas mowers only): Fuel older than 30 days may have degraded. If the mower has been stored for months, drain old fuel and replace it.
How to Start a Gas-Powered Lawnmower
Gas-powered mowers are the most common residential type. The startup sequence involves fuel delivery, air mixing, and ignition timing.
Preparation Steps
- Check the fuel level: Open the fuel cap and visually inspect the tank. Most residential mowers use regular unleaded gasoline (87 octane). Fill to just below the filler neck—do not overfill, as fuel can overflow during operation.
- Verify the oil level: Locate the dipstick (usually on the side of the engine) and pull it out. Wipe it clean, reinsert it fully, then pull it out again to check the level. The oil should reach the “full” mark. If low, add the recommended oil type (typically 10W-30 for most residential mowers). Running a mower with insufficient oil can cause engine damage.
- Inspect the spark plug: Remove the spark plug wire by twisting gently. Unscrew the spark plug with a spark plug socket. The electrode gap should be approximately 0.025–0.030 inches. If the plug is fouled (black, wet, or heavily soiled), replace it. A clean spark plug is essential for reliable ignition.
- Set the fuel shut-off valve to “On”: If your mower has a fuel valve (common on older models), make sure it is open. The valve is usually located where the fuel line connects to the carburetor.
Choke and Primer Bulb
The choke restricts airflow to the engine, creating a richer fuel mixture for cold starts. The primer bulb (if present) manually pumps fuel into the carburetor.
- Locate the choke lever on the side or top of the engine. It is usually labeled “Cold” and “Warm.”
- Move the lever to the “Cold” position (or full choke). This enriches the fuel mixture, making ignition easier in a cold engine.
- If your mower has a primer bulb (a rubber button on the carburetor), press it 3–6 times slowly. You will feel resistance as fuel is drawn into the carburetor. Do not over-prime, as this can flood the engine.
Pulling the Starter Cord
- Grip the handle firmly with one hand. Place your other hand on the mower body or handlebar to stabilize it.
- Locate the starter cord handle. Pull it straight toward you in one smooth, quick motion. Avoid yanking abruptly, which can cause the cord to snap or the engine to lock.
- If the engine does not start, wait 10–15 seconds and try again. Do not pull the cord more than 6–10 times in succession; this can flood the engine.
- Once the engine fires, you may hear it catch briefly. Continue pulling steadily until it runs consistently.
Warming Up
After the engine starts, let it idle for 30 seconds to one minute. Move the choke to the “Warm” or “Run” position as the engine warms. You will hear the engine smooth out. Once stable, the mower is ready to use. If the engine stalls when you move the choke, return it halfway to the cold position and wait another 30 seconds before trying again.
How to Start an Electric Lawnmower
Electric mowers—both cordless (battery-powered) and corded (plug-in)—offer simpler startup with minimal maintenance.
Cordless (Battery-Powered) Mowers
- Charge the battery fully before first use: Lithium-ion batteries (the most common type) typically require 30–90 minutes for a full charge, depending on capacity. Many manufacturers recommend charging overnight before the first use.
- Insert the battery into the mower: The battery slides or clicks into a port on the mower, usually near the handle. Ensure it is seated firmly; you will hear or feel a click when it locks.
- Press the power button: Most cordless mowers have a start button on the handle. Press and hold it for 1–2 seconds. The motor will engage immediately. No warming up is needed.
- Monitor battery life: Most cordless mowers run for 20–60 minutes per charge, depending on battery size and cutting conditions. Dense or tall grass drains the battery faster.
Corded (Plug-In) Mowers
- Inspect the power cord: Check for cuts, cracks, or damage to the insulation. Never use a damaged cord.
- Plug into a grounded outdoor outlet: Use a ground-fault circuit interrupter (GFCI) outlet for added safety. Standard household outlets are acceptable, but GFCI outlets reduce the risk of electrical shock.
- Press the power button: Corded mowers start instantly when you depress the start button. Keep the cord away from the blade path and do not allow it to tangle around your feet or the mower.
- No downtime limitations: Corded mowers run indefinitely as long as they remain plugged in. They are ideal for small to medium yards without the battery management of cordless models.
How to Start a Manual Push Lawnmower
Reel (manual push) mowers have no engine and require no fuel, spark plugs, or electrical systems. They are mechanically simple and eco-friendly.
- Inspect the blades: The cutting mechanism consists of a rotating spiral blade (the reel) and a fixed blade beneath it. Ensure both are clean and free of grass clippings and debris.
- Check for rust or corrosion: If the reel or frame shows rust, apply a light oil and work the handle back and forth to loosen it.
- Adjust the blade height: Most manual mowers have a lever on the wheels that adjusts cutting height. Set it to your desired height—typically 2–3 inches for most lawns.
- Begin pushing: Apply even, steady pressure as you push the mower forward. The wheels turn the reel, which cuts the grass between the reel and fixed blade. No engine startup is required.
- Maintenance note: After each use, rinse the reel and blades with a hose to prevent rust. Periodically sharpen the blades with a reel mower file to maintain a clean cut.
Troubleshooting Common Startup Problems
The Engine Won’t Start (Gas Mowers)
Possible causes and fixes:
- Flooded engine: If you have pulled the starter cord 10+ times without success, the engine is likely flooded (too much fuel in the combustion chamber). Remove the spark plug and pull the starter cord 6–8 times to clear excess fuel from the cylinder. Reinstall the spark plug, move the choke to the “Warm” position, and try starting again.
- Fouled or gapped spark plug: A dirty, wet, or incorrectly gapped spark plug prevents ignition. Remove and inspect the plug. If it is black or wet, replace it. If reusing it, clean the electrode with a wire brush and ensure the gap is 0.025–0.030 inches.
- Old or stale fuel: Fuel degrades after 30 days of storage. If the mower has been unused for months, drain the old fuel and replace it with fresh gasoline. Old fuel leaves varnish in the carburetor, restricting fuel flow.
- Clogged carburetor: If the mower has sat unused for an extended period, fuel residue can clog the carburetor. Use carburetor cleaner spray to flush the fuel ports. In severe cases, professional carburetor cleaning may be needed.
- Dead battery (electric start models): If your gas mower has an electric starter, a weak or dead battery will prevent ignition. Charge the battery or use the pull-cord backup starter.
The Engine Starts But Stalls Immediately
- Choke is too warm: The engine is still cold. Move the choke back to the “Cold” position and let it idle for 30–60 seconds.
- Carburetor needs cleaning: Stalling shortly after starting suggests fuel flow issues. Apply carburetor cleaner to clear blockages.
- Air filter is clogged: A dirty air filter restricts fuel-air mixing. Remove the air filter (typically a foam or paper element on top of the engine) and tap it gently to dislodge debris. If very dirty, replace it.
Electric Mower Won’t Start
- Battery not fully charged: Allow the battery to charge for the full recommended time (typically 30–90 minutes). Partially charged batteries may not have enough power.
- Battery not inserted correctly: Remove and reinsert the battery, ensuring you hear a firm click.
- Dead battery: If the mower is several years old, the battery may have reached the end of its lifespan. Most lithium-ion batteries last 3–5 years. Replace with a manufacturer-approved battery.
- Faulty power button or safety switch: Corded mowers have a safety switch that prevents accidental starting. Ensure the safety switch (usually a lever below the button) is engaged. If the button does not respond, the electrical switch may be defective and require professional repair.
Seasonal Startup: After Winter Storage
Restarting a mower after months of storage requires attention to fuel degradation and component condition.
Fuel Preparation
- Drain old fuel: If the mower was stored with fuel in the tank, drain it completely. Unscrew the fuel drain plug (located on the bottom of the fuel tank) into a container, or use a hand siphon pump to remove fuel through the filler neck.
- Fill with fresh fuel: Add fresh, high-quality gasoline. Never use fuel older than 30 days.
- Consider fuel stabilizer: If you plan to store the mower for more than 30 days in the future, add a fuel stabilizer before storage. This prevents varnish buildup and extends fuel life to 12 months.
Component Checks
- Change the oil: After winter storage, change the engine oil. Drain old oil by loosening the drain plug or using a hand pump, then refill with fresh oil appropriate for the engine type.
- Inspect the spark plug: Remove and inspect the spark plug. Replace if fouled or corroded.
- Check the air filter: Replace the air filter if it appears clogged or hasn’t been changed in over a season.
- Inspect fuel lines and connections: Look for cracks, leaks, or loose fittings. Tighten or replace as needed.
First Start After Storage
After performing the above steps, attempt to start the mower. It may require 8–12 pulls of the starter cord before the engine catches, as fuel lines need to refill and the engine needs to prime. If it does not start after 15 pulls, stop and review the troubleshooting section above.
Frequently Asked Questions
What type of fuel does a gas lawnmower use?
Most residential gas lawnmowers use regular unleaded gasoline with an octane rating of 87. Check your mower’s manual for specific fuel recommendations. Avoid premium fuel (91+ octane) unless the manual specifies it, as it offers no benefit for small engines and may cause carbon buildup. Never use diesel fuel or fuel older than 30 days in storage.
How often should I check the oil in my gas lawnmower?
Check the oil level before each use, especially during the mowing season. The oil should reach the “full” mark on the dipstick when the mower is on level ground. Change the oil at least once per season, typically in spring before heavy use. If you mow frequently, change it every 50 hours of operation. Fresh oil keeps the engine lubricated and helps it start reliably.
Why won’t my cordless electric mower start after I store it for winter?
Lithium-ion batteries lose charge slowly over time, even when not in use. If a cordless mower hasn’t been used for several months, the battery may be nearly dead. Charge it fully—allow 30–90 minutes depending on capacity. If it still won’t start after a full charge, the battery may be defective and require replacement. Many manufacturers warrant batteries for 2–3 years; contact customer support if the battery is within warranty.
Is it safe to use a gas lawnmower in wet grass?
Using a gas lawnmower on wet grass increases the risk of slipping and losing control. Additionally, wet grass clumps in the deck and can jam the blade. For safety and best results, allow the grass to dry for a few hours after rain or watering before mowing. Electric mowers (both cordless and corded) should never be used in wet conditions due to electrical hazards.
