Lawn mower smoking: Common Causes & How to Fix
1Lawn Mower Carburetor
Most Common Solution
Repair Instructions:
Black smoke from your lawnmower's engine points to the carburetor getting an excess of fuel, a condition known as "running rich." This occurs if the carburetor float, which moderates fuel flow, remains open, allowing too much fuel in. On the other hand, if the carburetor choke, which manages air supply, is stuck in a closed position, the mower engine can't pull in enough air. Both scenarios disrupt the ideal mix of air and fuel needed for your lawnmower to function correctly.
How to Replace Lawn Mower Carburetor
- Disconnect the spark plug wire - Locate the spark plug wire and detach it from the spark plug. This will prevent accidental starting while working.
- Drain the gas tank - Use a siphon or tip the mower to drain all gasoline from the fuel tank into an approved gas container. This minimizes spillage when removing the carburetor.
- Remove air filter - Take out the air filter housing and remove the air filter element. This allows access to the carburetor.
- Detach fuel line - Locate the fuel supply line attached to the carburetor inlet and disconnect it using pliers. Cap the end of the fuel line.
- Remove carburetor retaining nuts - Use a socket or wrench to loosen the carburetor retaining nuts attaching it to the engine intake manifold.
- Detach choke and throttle links - Remove any fasteners or rings connecting the choke and throttle controls from the carburetor levers.
- Lift off the old carburetor - Carefully lift the carburetor off of the intake manifold studs. Take care not to bend or damage linkages.
- Install new carburetor - Place the new carburetor onto the intake manifold studs. Reattach the choke, throttle, fuel line, air filter housing and retaining nuts.
- Reconnect spark plug wire - Attach the spark plug wire to the spark plug once done.
- Test operation - Add fresh gasoline to the fuel tank. Try starting the mower to ensure proper carburetor operation before fully reassembling. Make adjustments as needed.
2Lawn Mower Carburetor Repair Kit
Most Common Solution
Repair Instructions:
Black smoke from a lawnmower engine suggests that it's getting too much fuel from the carburetor, also known as "running rich". This can happen if the carburetor float, which controls fuel intake, is stuck open, leading to excessive fuel. Also, if the carburetor choke, which adjusts air flow, is stuck closed, the engine can't take in enough air. Both situations disrupt the ideal air and fuel balance needed for smooth operation.
How to Replace Lawn Mower Carburetor Repair Kit
- Remove air filter - Detach the air filter housing and remove the air filter element to access the carburetor.
- Drain fuel - Empty the gas from the fuel tank using a siphon or by tipping the mower. This reduces spillage when removing carburetor.
- Detach fuel line - Use pliers to disconnect the fuel supply line from the carburetor inlet. Cap the fuel line.
- Remove carburetor - Take out the retaining nuts and detach any choke/throttle links to fully remove the carburetor.
- Disassemble carburetor - Taking care to organize parts, fully disassemble the carburetor by removing gaskets, jets, float and needle.
- Clean carburetor parts - Use carburetor cleaner spray and small wire brushes to clean all removable parts and passages.
- Install new parts - Replace old gaskets, seals, and worn components with matching parts from the repair kit.
- Reassemble carburetor - Following proper assembly procedures, reinstall float, needle, jets, gaskets and other parts into the cleaned carburetor.
- Install carburetor - Mount the rebuilt carburetor back onto the engine and reconnect fuel line, air filter, choke/throttle links.
- Test operation - Add fresh gas to the fuel tank. Try starting the mower to ensure proper carburetor operation. Make adjustments as needed.
3Carburetor is Letting Too Much Fuel In
Repair Instructions:
When your lawnmower blows out black smoke, it means it's getting too much fuel, a situation also known as "running rich." This can happen if the carburetor float, which controls fuel flow, is stuck open, causing too much fuel to enter. Similarly, if the carburetor choke, which controls air intake, is stuck closed, the engine won't get enough air. Both these problems mess up the right balance of air and fuel your lawnmower needs to work properly.
How to Replace Lawn Mower Carburetor Repair Kit
- Remove air filter - Detach the air filter housing and remove the air filter element to access the carburetor.
- Drain fuel - Empty the gas from the fuel tank using a siphon or by tipping the mower. This reduces spillage when removing carburetor.
- Detach fuel line - Use pliers to disconnect the fuel supply line from the carburetor inlet. Cap the fuel line.
- Remove carburetor - Take out the retaining nuts and detach any choke/throttle links to fully remove the carburetor.
- Disassemble carburetor - Taking care to organize parts, fully disassemble the carburetor by removing gaskets, jets, float and needle.
- Clean carburetor parts - Use carburetor cleaner spray and small wire brushes to clean all removable parts and passages.
- Install new parts - Replace old gaskets, seals, and worn components with matching parts from the repair kit.
- Reassemble carburetor - Following proper assembly procedures, reinstall float, needle, jets, gaskets and other parts into the cleaned carburetor.
- Install carburetor - Mount the rebuilt carburetor back onto the engine and reconnect fuel line, air filter, choke/throttle links.
- Test operation - Add fresh gas to the fuel tank. Try starting the mower to ensure proper carburetor operation. Make adjustments as needed.