Student-Contributed Wiki

Student-Contributed Wiki

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The Engine Will Not Start ¶ 

The pull cord is free to move, but the engine will not start

The Pull Cord Needs a Harder Tug ¶ 

Small gas engines require human power to get going. Pulling the starter rope gets the piston moving and generates the electrical power to spark ignition. This requires a good amount of force so make sure that you put in a few consecutive strong tugs before assuming something is wrong. Check out a pull cord replacement.

The Fuel Tank is Empty / The Fuel is Bad ¶ 

Lawn mower engines run on gasoline held in a small tank on the backside of the engine. Like cars, the engine will not start without fuel. Make sure there is fuel in the tank. Fuel that has been sitting for long periods of time can also go bad. Consider draining old fuel and refilling the tank with new gasoline.

The Spark Plug is Bad / The Spark Plug Needs Love ¶ 

The spark plug is a cylindrical piece the size of your thumb that can be found on the front side of the engine. It is made of silver metal and white ceramic and is what ignites the fuel in the engine. Spark plugs will wear out after extended use so make sure to check it. The spark plug can also be disabled if it is unplugged, dirty or misaligned so make sure it is clean, plugged in to the black electrical lead, and screwed in tight. Check out a spark plug replacement.

The Air Filter is Clogged ¶ 

The air filter can be found on the left side of the engine and is a consumable component. Air filters need to be replaced regularly and if clogged, will prevent engine start up. This is because the air filter provides clean air to the combustion chamber. If it is clogged, no air will reach the engine and it will not start. To replace the air filter, check out this guide.

The Fuel Filter is Clogged ¶ 

The fuel filter cleans the gasoline on its way through the engine. If clogged, it will prevent fuel flow and the engine will not start.

Note: Sometimes the fuel line just needs a few taps to allow fuel to pass though. give this a try before taking your engine apart.

The Engine Stops in the Middle of Mowing ¶ 

The engine starts up fine, but stops or seizes while mowing

The Fuel Tank is Empty / The Fuel is Bad ¶ 

Lawn mower engines run on gasoline held in a small tank on the backside of the engine. Like cars, the engine will not start without fuel. Make sure there is fuel in the tank. Fuel that has been sitting for long periods of time can also go bad. Consider draining old fuel and refilling the tank with new gasoline.

There is No Oil / The Oil is Low ¶ 

Oil is very important to any mechanical machine. It keeps the parts moving smoothly and without it, your engine can become sluggish or even seize up. You can check your oil level using the dipstick located on the inside of your oil cap. If the oil level is low, make sure to replace the oil before running the mower again. for help with this, check out this guide.

The Air Filter is Clogged ¶ 

The air filter can be found on the left side of the engine and is a consumable component. Air filters need to be replaced regularly and if clogged, they will prevent the engine from running. This is because the air filter provides clean air to the combustion chamber. If it is clogged, no air will reach the engine and it will not run. To replace the air filter, check out this guide.

The Spark Plug is Dirty / The Spark Plug is Misaligned ¶ 

The spark plug is a cylindrical piece the size of your thumb that can be found on the front side of the engine. It is made of silver metal and white ceramic and is what ignites the fuel in the engine. The spark plug can be disabled or fire irregularly if it is dirty or misaligned so make sure it is clean and screwed in tight. Check out a spark plug replacement.

The Engine is Smoking ¶ 

The engine starts emitting smoke when turned on

There May Not be a Problem ¶ 

Internal combustion engines like this lawnmower engine burn fuel to generate power. When the engine is first turned on, it is not uncommon for it to puff out white smoke until the system heats up.

The Oil is Leaking / The O-Ring has Failed ¶ 

If the engine continues to smoke after extended use, or emits a dark colored smoke, you may have an oil problem. If oil is allowed to enter the combustion chamber, it will burn producing large quantities of smoke. This could be due to an oil leak somewhere in the engine or a failure of the o-rings surrounding the cylinder. Both of these issues are relatively serious but uncommon. Both would require repairs beyond the scope of the guides on this site.

The Engine Makes an Abnormally Loud and Unusual Noise ¶ 

When the engine is turned on, it makes a noise unusual to the mower

The Muffler has Failed ¶ 

The muffler, located on the left side of the engine, is responsible for lowering the volume of the outputted engine noise. It does this by sending the engine exhaust through a series of metal baffles that lower the energy of the gas. Over time, the muffler can become damaged by use and can fail to perform its function. If this happens, you can replace the muffler using this guide.

General Maintenance Problems ¶ 

Gas engines have many moving parts and produce a lot of mechanical vibrations when running. If your engine is making a strange sound such as a rattle or squeak, do a general check of the engines components. Check the oil level to make sure it has enough lubrication, check the bolts that hold the engine in place to make sure they are tight and check the spark plug to make sure it is in the proper position. General maintenance problems could cause abnormal vibration or friction that can be audible.

5 Comments

Front tires are not pulling.

fairlane64 - Reply

front tires are not pulling, belt is connected and turning when motor is running.

fairlane64 - Reply

turned it up side down (the lower half - the mower ) and dark blaskish opil spilled out of it. how to replace refill the oil ? there's no manual for this .

gothic81 - Reply

my briggs & stratton 675 engine series takes a while to start up and when it does start up the engine is weak how can i fix this

Austin - Reply

when i took it apart i found that my fuel intake valve wasnt moving and my engine had no compression

Austin - Reply

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