A sputtering lawnmower on a Saturday morning is a gardener's worst nightmare. Briggs & Stratton engines power millions of lawnmowers, snowblowers, and other outdoor power equipment. When these engines fail to start or run smoothly, it can be frustrating. But don't despair! Most issues have simple solutions that you can tackle yourself with a bit of know-how and a few basic tools. This guide will walk you through common Briggs & Stratton problems and offer quick fixes to get your equipment back up and running.
My Engine Won't Start - Where Do I Even Begin?
The dreaded no-start situation! Before you start tearing things apart, let's go through a logical checklist. Often, the culprit is something surprisingly simple.
Fuel, Fuel, Fuel: This is the most common cause. Is there gas in the tank? Don't just assume there is; visually check. Stale fuel is another big problem. Gasoline can degrade and lose its combustibility, especially if it's been sitting for several months. If your fuel is older than 30 days, drain it and replace it with fresh fuel. Use fuel stabilizer in fresh gasoline for optimal results.
Spark Plug Check: Remove the spark plug (after allowing the engine to cool completely, of course!). Inspect it for cracks, fouling (black, oily residue), or corrosion. A healthy spark plug should be clean and dry. If it's dirty, try cleaning it with a wire brush. If it's damaged, replace it. To test if it's sparking, reattach the spark plug wire, hold the plug against the engine block (metal part), and pull the starter cord. You should see a strong, blue spark. No spark? Replace the spark plug. Still no spark? The ignition coil might be faulty (more on that later).
Air Filter Inspection: A clogged air filter restricts airflow to the engine, preventing it from starting. Remove the air filter and inspect it. If it's dirty, gently tap it to remove loose debris. If it's excessively dirty or oily, replace it. Don't run the engine without an air filter, even for a short time, as this can damage the engine.
Safety Interlocks: Many lawnmowers have safety features that prevent them from starting if certain conditions aren't met. Make sure the blade engagement lever is disengaged, the parking brake is engaged (if applicable), and the operator presence control (if present) is properly engaged. A common issue is the operator presence control on riding mowers. Ensure the seat switch is functioning correctly.
Oil Level: Low oil levels can also prevent the engine from starting. Check the oil level using the dipstick and add oil as needed. Always use the type of oil recommended in your owner's manual.
The Engine Starts, But It Runs Rough or Stalls
Okay, so your engine starts, but it's not happy. Here are some common causes of rough running or stalling:
Carburetor Issues: The carburetor mixes air and fuel to create the combustible mixture for the engine. If it's clogged or dirty, it can cause problems. Carburetor issues are especially common if the engine has been sitting for a long time.
Cleaning the Carburetor: Sometimes, a simple cleaning can do the trick. You can try using carburetor cleaner spray. Remove the air filter and spray the cleaner into the carburetor intake while the engine is running (if it will run). This can help dissolve some of the deposits. For a more thorough cleaning, you'll need to remove the carburetor and disassemble it. This involves removing the bowl, jets, and other small parts. Clean each part with carburetor cleaner and a small brush. Be sure to keep track of all the parts and reassemble them correctly. Many online videos show how to clean specific Briggs & Stratton carburetors.
Carburetor Adjustment: Some carburetors have adjustment screws that allow you to fine-tune the air/fuel mixture. Refer to your owner's manual for instructions on how to adjust the carburetor. Incorrect adjustments can lead to poor performance or engine damage, so proceed with caution.
Fuel Line Problems: Cracked or clogged fuel lines can restrict fuel flow to the engine. Inspect the fuel lines for any signs of damage or blockage. Replace any damaged lines. You can also try blowing compressed air through the fuel lines to clear any blockages.
Dirty Fuel Filter: Many Briggs & Stratton engines have a small fuel filter in the fuel line. This filter can become clogged with debris, restricting fuel flow. Replace the fuel filter if it's dirty.
Valve Problems: Valve issues are less common but can cause significant problems. Worn or damaged valves can prevent the engine from running properly. This often requires professional repair.
Dealing with a Flooded Engine
Sometimes, you can flood the engine by pulling the starter cord too many times or by over-priming it. A flooded engine has too much fuel in the cylinder, preventing it from igniting.
The Classic Flooding Fix: The easiest way to deal with a flooded engine is to wait. Simply let the engine sit for 15-30 minutes to allow the excess fuel to evaporate. Then, try starting it again without using the primer.
The "Choke Off" Method: If waiting doesn't work, try this: Turn the choke off (or to the "run" position), and then pull the starter cord several times with the throttle wide open. This helps to clear the excess fuel from the cylinder.
Spark Plug Removal (Advanced): If the above methods fail, you can remove the spark plug and pull the starter cord several times to expel the excess fuel from the cylinder. Then, dry the spark plug and reinstall it.
The Engine Smokes - What's Going On?
Engine smoke can indicate various problems, depending on the color of the smoke:
Blue Smoke: This usually indicates that the engine is burning oil. Common causes include worn piston rings, worn valve guides, or overfilling the oil. Burning oil can lead to engine damage, so it's important to address the problem promptly. Check the oil level and make sure it's not overfilled. If the problem persists, you may need to have the engine professionally repaired.
Black Smoke: This usually indicates that the engine is running too rich (too much fuel). This can be caused by a dirty air filter, a faulty carburetor, or a clogged fuel filter. Check the air filter and fuel filter and replace them if necessary. If the problem persists, you may need to have the carburetor adjusted.
White Smoke: This can indicate several things, including burning coolant (if the engine is liquid-cooled), burning condensation, or a blown head gasket. If the engine is producing excessive white smoke and overheating, it's important to stop using it immediately and seek professional help.
Ignition Coil Issues: No Spark? Here's What to Do
If you've ruled out the spark plug as the problem and you're still not getting a spark, the ignition coil is likely the culprit. The ignition coil is responsible for generating the high-voltage spark that ignites the fuel mixture.
Testing the Ignition Coil: You'll need a multimeter to test the ignition coil. Disconnect the spark plug wire and the ignition coil wires. Set the multimeter to the ohms setting. Connect the multimeter probes to the ignition coil terminals. The resistance reading should be within the range specified in your owner's manual. If the resistance is outside the specified range, the ignition coil is likely faulty and needs to be replaced.
Replacing the Ignition Coil: Replacing the ignition coil is a relatively straightforward process. Remove the engine cover to access the ignition coil. Disconnect the spark plug wire and the ignition coil wires. Remove the mounting screws and remove the old ignition coil. Install the new ignition coil in the reverse order. Make sure the air gap between the ignition coil and the flywheel is correct. Refer to your owner's manual for the correct air gap specification.
Troubleshooting the Recoil Starter
The recoil starter is the mechanism you use to manually start the engine. If it's not working properly, you won't be able to start the engine.
Rope is Stuck: If the rope is stuck and won't pull, it could be due to a binding recoil mechanism or a seized engine. Try turning the engine flywheel by hand. If it turns freely, the recoil mechanism is likely the problem. If the flywheel is stuck, the engine may be seized, which is a serious problem.
Rope is Broken: If the rope is broken, you'll need to replace it. Remove the recoil starter assembly from the engine. Remove the broken rope and install a new one. Make sure to wind the rope correctly around the pulley.
Recoil Spring is Broken: If the recoil spring is broken, the rope won't retract properly. You'll need to replace the recoil spring. This can be a tricky process, as the spring is under tension. Wear safety glasses and gloves when working with the recoil spring.
Prevention is Better Than Cure: Keeping Your Briggs & Stratton Engine Healthy
Regular maintenance is key to preventing problems with your Briggs & Stratton engine.
- Regular Oil Changes: Change the oil regularly, as recommended in your owner's manual.
- Clean or Replace the Air Filter: Clean or replace the air filter regularly, as needed.
- Use Fresh Fuel: Use fresh fuel and add fuel stabilizer to prevent fuel degradation.
- Clean the Engine: Keep the engine clean and free of debris.
- Sharpen Blades (for lawnmowers): Keep your lawnmower blades sharp for optimal performance.
Frequently Asked Questions
Why won't my lawnmower start after winter storage? Stale fuel is the most common culprit. Drain the old fuel and replace it with fresh fuel.
How often should I change the oil in my lawnmower? Refer to your owner's manual, but generally, change the oil every 25-50 hours of use, or at least once a year.
What type of oil should I use in my Briggs & Stratton engine? Use the type of oil recommended in your owner's manual. SAE 30 is a common choice for many small engines.
Can I use automotive gasoline in my lawnmower? Yes, but it's best to use gasoline with an octane rating of 87 or higher and avoid gasoline with ethanol if possible.
My lawnmower is vibrating excessively. What could be the cause? This could be due to a bent crankshaft, loose blades, or an unbalanced blade. Inspect these components and repair or replace as needed.
The Takeaway
Troubleshooting a Briggs & Stratton engine doesn't have to be daunting. By following these simple steps and performing regular maintenance, you can keep your equipment running smoothly for years to come. Remember safety first and consult your owner's manual for specific instructions related to your engine model.